diff --git a/README.third_party.md b/README.third_party.md
index 1c8129b08de..02eff8a7acf 100644
--- a/README.third_party.md
+++ b/README.third_party.md
@@ -50,7 +50,7 @@ a notice will be included in
 | [LibTomCrypt]                                        | WTFPL, Public Domain                                                                                | 1.18.2                                   | ✗                    | ✗                               |
 | [libunwind/libunwind]                                | MIT                                                                                                 | v1.8.1                                   |                      | ✗                               |
 | [linenoise]                                          | BSD-2-Clause                                                                                        | Unknown                                  |                      | ✗                               |
-| [MongoDB C Driver]                                   | Apache-2.0                                                                                          | 1.27.6                                   | ✗                    | ✗                               |
+| [MongoDB C Driver]                                   | Apache-2.0                                                                                          | 1.28.1                                   | ✗                    | ✗                               |
 | [Mozilla Firefox]                                    | MPL-2.0                                                                                             | 128.8.0esr                               | unknown              | ✗                               |
 | [nlohmann-json]                                      | MIT                                                                                                 | 3.11.3                                   | ✗                    |                                 |
 | [nlohmann.json.decomposed]                           | MIT                                                                                                 | 3.10.5                                   | unknown              |                                 |
diff --git a/bazel/mongo_src_rules.bzl b/bazel/mongo_src_rules.bzl
index 334893417c2..e2824ee58d5 100644
--- a/bazel/mongo_src_rules.bzl
+++ b/bazel/mongo_src_rules.bzl
@@ -1574,7 +1574,7 @@ def force_includes_hdr(package_name, name):
 
     return []
 
-# TODO(SERVER-102596): Stop including this flag when ASP is able to upgrade mongoc and mongocxx
+# TODO(SERVER-103006): Stop including this flag when ASP is able to upgrade mongoc and mongocxx
 STREAMS_THIRD_PARTY_DIR = "src/mongo/db/modules/enterprise/src/streams/third_party"
 
 def package_specific_copt(package_name):
diff --git a/sbom.json b/sbom.json
index f65fb9c0a31..9c7afa81131 100644
--- a/sbom.json
+++ b/sbom.json
@@ -1191,7 +1191,7 @@
         "name": "Organization: github"
       },
       "name": "MongoDB C Driver",
-      "version": "1.27.6",
+      "version": "1.28.1",
       "licenses": [
         {
           "license": {
@@ -1199,7 +1199,7 @@
           }
         }
       ],
-      "purl": "pkg:github/mongodb/mongo-c-driver@1.27.6",
+      "purl": "pkg:github/mongodb/mongo-c-driver@1.28.1",
       "properties": [
         {
           "name": "internal:team_responsible",
diff --git a/src/third_party/libbson/dist/src/common/common-b64-private.h b/src/third_party/libbson/dist/src/common/common-b64-private.h
index 7f5c4e35d7d..4ef5fbd3db1 100644
--- a/src/third_party/libbson/dist/src/common/common-b64-private.h
+++ b/src/third_party/libbson/dist/src/common/common-b64-private.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2018-present MongoDB Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/common/common-macros-private.h b/src/third_party/libbson/dist/src/common/common-macros-private.h
index 360a0f51ead..e739710a430 100644
--- a/src/third_party/libbson/dist/src/common/common-macros-private.h
+++ b/src/third_party/libbson/dist/src/common/common-macros-private.h
@@ -1,3 +1,18 @@
+/*
+ * Copyright 2009-present MongoDB, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
 
 #include "common-prelude.h"
 
@@ -12,4 +27,32 @@
 #define MONGOC_DEBUG_ASSERT(statement) ((void) 0)
 #endif
 
+// `MC_ENABLE_CONVERSION_WARNING_BEGIN` enables -Wconversion to check for potentially unsafe integer conversions.
+// The `bson_in_range_*` functions can help address these warnings by ensuring a cast is within bounds.
+#if (__GNUC__ > 4) || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6) // gcc 4.6 added support for "diagnostic push".
+#define MC_ENABLE_CONVERSION_WARNING_BEGIN \
+   _Pragma ("GCC diagnostic push") _Pragma ("GCC diagnostic warning \"-Wconversion\"")
+#define MC_ENABLE_CONVERSION_WARNING_END _Pragma ("GCC diagnostic pop")
+#elif defined(__clang__)
+#define MC_ENABLE_CONVERSION_WARNING_BEGIN \
+   _Pragma ("clang diagnostic push") _Pragma ("clang diagnostic warning \"-Wconversion\"")
+#define MC_ENABLE_CONVERSION_WARNING_END _Pragma ("clang diagnostic pop")
+#else
+#define MC_ENABLE_CONVERSION_WARNING_BEGIN
+#define MC_ENABLE_CONVERSION_WARNING_END
 #endif
+
+// Disable the -Wcast-function-type-strict warning.
+#define MC_DISABLE_CAST_FUNCTION_TYPE_STRICT_WARNING_BEGIN
+#define MC_DISABLE_CAST_FUNCTION_TYPE_STRICT_WARNING_END
+#if defined(__clang__)
+#if __has_warning("-Wcast-function-type-strict")
+#undef MC_DISABLE_CAST_FUNCTION_TYPE_STRICT_WARNING_BEGIN
+#undef MC_DISABLE_CAST_FUNCTION_TYPE_STRICT_WARNING_END
+#define MC_DISABLE_CAST_FUNCTION_TYPE_STRICT_WARNING_BEGIN \
+   _Pragma ("clang diagnostic push") _Pragma ("clang diagnostic ignored \"-Wcast-function-type-strict\"")
+#define MC_DISABLE_CAST_FUNCTION_TYPE_STRICT_WARNING_END _Pragma ("clang diagnostic pop")
+#endif // __has_warning("-Wcast-function-type-strict")
+#endif // defined(__clang__)
+
+#endif /* COMMON_MACROS_PRIVATE_H */
diff --git a/src/third_party/libbson/dist/src/common/common-md5-private.h b/src/third_party/libbson/dist/src/common/common-md5-private.h
index 4feadb93154..a77d232df46 100644
--- a/src/third_party/libbson/dist/src/common/common-md5-private.h
+++ b/src/third_party/libbson/dist/src/common/common-md5-private.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2018-present MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/common/common-prelude.h b/src/third_party/libbson/dist/src/common/common-prelude.h
index 4f3a5fdd024..cc73b338d0b 100644
--- a/src/third_party/libbson/dist/src/common/common-prelude.h
+++ b/src/third_party/libbson/dist/src/common/common-prelude.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2018-present MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/common/common-thread-private.h b/src/third_party/libbson/dist/src/common/common-thread-private.h
index 291af21a90e..29ace085ddd 100644
--- a/src/third_party/libbson/dist/src/common/common-thread-private.h
+++ b/src/third_party/libbson/dist/src/common/common-thread-private.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-present MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/common/common-thread.c b/src/third_party/libbson/dist/src/common/common-thread.c
index 9b26f6e9567..dbebd97727e 100644
--- a/src/third_party/libbson/dist/src/common/common-thread.c
+++ b/src/third_party/libbson/dist/src/common/common-thread.c
@@ -1,5 +1,5 @@
 /*
- * Copyright 2020-present MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,7 +24,7 @@ mcommon_thread_create (bson_thread_t *thread, BSON_THREAD_FUN_TYPE (func), void
 {
    BSON_ASSERT_PARAM (thread);
    BSON_ASSERT_PARAM (func);
-   BSON_ASSERT (arg || true); // optional.
+   BSON_OPTIONAL_PARAM (arg); // optional.
    return pthread_create (thread, NULL, func, arg);
 }
 int
@@ -47,7 +47,7 @@ mcommon_thread_create (bson_thread_t *thread, BSON_THREAD_FUN_TYPE (func), void
 {
    BSON_ASSERT_PARAM (thread);
    BSON_ASSERT_PARAM (func);
-   BSON_ASSERT (arg || true); // optional.
+   BSON_OPTIONAL_PARAM (arg); // optional.
 
    *thread = (HANDLE) _beginthreadex (NULL, 0, func, arg, 0, NULL);
    if (0 == *thread) {
diff --git a/src/third_party/libbson/dist/src/libbson/NEWS b/src/third_party/libbson/dist/src/libbson/NEWS
index 7d21ef5f05b..c90b5738358 100644
--- a/src/third_party/libbson/dist/src/libbson/NEWS
+++ b/src/third_party/libbson/dist/src/libbson/NEWS
@@ -1,3 +1,33 @@
+libbson 1.28.1
+==============
+
+Fixes:
+
+  * Fix large string handling in `bson_string_truncate`.
+  * Fix possible crash in `bson_value_copy`.
+
+
+Thanks to everyone who contributed to the development of this release.
+
+  * Joshua Siegel
+  * Kevin Albertson
+
+
+
+libbson 1.28.0
+==============
+
+New features:
+
+  * Add `bson_validate_with_error_and_offset`.
+
+Build Configuration:
+
+  * Remove automatic ccache detection and usage (CCache.cmake).
+      * Set [`CMAKE_<LANG>_COMPILER_LAUNCHER`](https://cmake.org/cmake/help/latest/envvar/CMAKE_LANG_COMPILER_LAUNCHER.html) to build with ccache.
+  * Remove `MONGO_USE_CCACHE` (no longer applicable; see above).
+
+
 libbson 1.27.6
 ==============
 
diff --git a/src/third_party/libbson/dist/src/libbson/libbson.rc.in b/src/third_party/libbson/dist/src/libbson/libbson.rc.in
index 2ba98064c45..47afe6f140b 100644
--- a/src/third_party/libbson/dist/src/libbson/libbson.rc.in
+++ b/src/third_party/libbson/dist/src/libbson/libbson.rc.in
@@ -34,7 +34,7 @@ BEGIN
             VALUE "OriginalFilename", BSON_OUTPUT_BASENAME "-" BSON_API_VERSION ".dll"
             VALUE "ProductName", "MongoDB C Driver"
             VALUE "ProductVersion", BSON_VERSION_S
-            VALUE "LegalCopyright", "Copyright (C) 2013-present MongoDB, Inc."
+            VALUE "LegalCopyright", "Copyright 2009-present MongoDB, Inc."
         END
     END
     BLOCK "VarFileInfo"
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bcon.c b/src/third_party/libbson/dist/src/libbson/src/bson/bcon.c
index 0779d89a96f..1835bd970b6 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bcon.c
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bcon.c
@@ -3,7 +3,7 @@
  * @brief BCON (BSON C Object Notation) Implementation
  */
 
-/*    Copyright 2009-2013 MongoDB, Inc.
+/*    Copyright 2009-present MongoDB, Inc.
  *
  *    Licensed under the Apache License, Version 2.0 (the "License");
  *    you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bcon.h b/src/third_party/libbson/dist/src/libbson/src/bson/bcon.h
index d35365e6e6a..b067078ecdd 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bcon.h
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bcon.h
@@ -5,7 +5,7 @@
 
 #include <bson/bson-prelude.h>
 
-/*    Copyright 2009-2013 MongoDB, Inc.
+/*    Copyright 2009-present MongoDB, Inc.
  *
  *    Licensed under the Apache License, Version 2.0 (the "License");
  *    you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-atomic.c b/src/third_party/libbson/dist/src/libbson/src/bson/bson-atomic.c
index 18dd4edb25e..64caa79bd45 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-atomic.c
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-atomic.c
@@ -1,5 +1,5 @@
 /*
- * Copyright 2014 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-atomic.h b/src/third_party/libbson/dist/src/libbson/src/bson/bson-atomic.h
index 60ab74c87ef..8195d8777f8 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-atomic.h
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-atomic.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2014 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -187,6 +187,7 @@ enum bson_memory_order {
             BSON_UNREACHABLE ("Invalid bson_memory_order value");                                                      \
       })                                                                                                               \
       BSON_IF_GNU_LEGACY_ATOMICS ({                                                                                    \
+         BSON_UNUSED (order);                                                                                          \
          __sync_synchronize ();                                                                                        \
          return *a;                                                                                                    \
       })                                                                                                               \
@@ -213,7 +214,7 @@ enum bson_memory_order {
          default:                                                                                                      \
             BSON_UNREACHABLE ("Invalid bson_memory_order value");                                                      \
       })                                                                                                               \
-      BSON_IF_GNU_LEGACY_ATOMICS (return __sync_val_compare_and_swap (a, *a, value);)                                  \
+      BSON_IF_GNU_LEGACY_ATOMICS (BSON_UNUSED (ord); return __sync_val_compare_and_swap (a, *a, value);)               \
    }                                                                                                                   \
                                                                                                                        \
    static BSON_INLINE Type bson_atomic_##NamePart##_compare_exchange_strong (                                          \
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-clock.c b/src/third_party/libbson/dist/src/libbson/src/bson/bson-clock.c
index a9510c2e3b7..959cbe13322 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-clock.c
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-clock.c
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-clock.h b/src/third_party/libbson/dist/src/libbson/src/bson/bson-clock.h
index a4845b7417d..4179152772a 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-clock.h
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-clock.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2014 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-cmp.h b/src/third_party/libbson/dist/src/libbson/src/bson/bson-cmp.h
index 5a90d0f1a6e..f5785f52173 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-cmp.h
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-cmp.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2022 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-compat.h b/src/third_party/libbson/dist/src/libbson/src/bson/bson-compat.h
index f403fb4c77b..eb28dcd3eab 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-compat.h
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-compat.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -36,11 +36,11 @@
 
 
 #ifdef BSON_OS_WIN32
-#if defined(_WIN32_WINNT) && (_WIN32_WINNT < 0x0600)
+#if defined(_WIN32_WINNT) && (_WIN32_WINNT < 0x0601)
 #undef _WIN32_WINNT
 #endif
 #ifndef _WIN32_WINNT
-#define _WIN32_WINNT 0x0600
+#define _WIN32_WINNT 0x0601
 #endif
 #ifndef NOMINMAX
 #define NOMINMAX
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-config.h.in b/src/third_party/libbson/dist/src/libbson/src/bson/bson-config.h.in
index 2849d0206a2..14254fba553 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-config.h.in
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-config.h.in
@@ -1,5 +1,5 @@
 /*
- * Copyright 2018-present MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-context-private.h b/src/third_party/libbson/dist/src/libbson/src/bson/bson-context-private.h
index 043497357b3..e260c55b17d 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-context-private.h
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-context-private.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2014 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-context.c b/src/third_party/libbson/dist/src/libbson/src/bson/bson-context.c
index f9f545f77ea..6b8eb67ec05 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-context.c
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-context.c
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-context.h b/src/third_party/libbson/dist/src/libbson/src/bson/bson-context.h
index 8399b57755b..882d080bbcb 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-context.h
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-context.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-decimal128.c b/src/third_party/libbson/dist/src/libbson/src/bson/bson-decimal128.c
index 786963c24cf..b1ccec1841b 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-decimal128.c
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-decimal128.c
@@ -1,6 +1,6 @@
 
 /*
- * Copyright 2015 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -269,7 +269,9 @@ bson_decimal128_to_string (const bson_decimal128_t *dec, /* IN  */
       }
       /* Exponent */
       *(str_out++) = 'E';
-      bson_snprintf (str_out, 6, "%+d", scientific_exponent);
+      // Truncation is OK.
+      int req = bson_snprintf (str_out, 6, "%+d", scientific_exponent);
+      BSON_ASSERT (req > 0);
    } else {
       /* Regular format with no decimal place */
       if (exponent >= 0) {
@@ -280,8 +282,11 @@ bson_decimal128_to_string (const bson_decimal128_t *dec, /* IN  */
       } else {
          int32_t radix_position = significand_digits + exponent;
 
+         // Reserve space for null terminator.
+         const int available_bytes = BSON_DECIMAL128_STRING - 1;
+
          if (radix_position > 0) { /* non-zero digits before radix */
-            for (int32_t i = 0; i < radix_position && (str_out - str) < BSON_DECIMAL128_STRING; i++) {
+            for (int32_t i = 0; i < radix_position && (str_out - str) < available_bytes; i++) {
                *(str_out++) = *(significand_read++) + '0';
             }
          } else { /* leading zero before radix point */
@@ -294,7 +299,7 @@ bson_decimal128_to_string (const bson_decimal128_t *dec, /* IN  */
          }
 
          for (uint32_t i = 0; bson_cmp_greater_us (significand_digits - i, BSON_MAX (radix_position - 1, 0)) &&
-                              (str_out - str) < BSON_DECIMAL128_STRING;
+                              (str_out - str) < available_bytes;
               i++) {
             *(str_out++) = *(significand_read++) + '0';
          }
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-decimal128.h b/src/third_party/libbson/dist/src/libbson/src/bson/bson-decimal128.h
index aa1d53afb0e..48d5f29ae98 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-decimal128.h
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-decimal128.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2015 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-endian.h b/src/third_party/libbson/dist/src/libbson/src/bson/bson-endian.h
index 1527f10887b..9b6cf9ef531 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-endian.h
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-endian.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,11 +20,6 @@
 #ifndef BSON_ENDIAN_H
 #define BSON_ENDIAN_H
 
-
-#if defined(__sun)
-#include <sys/byteorder.h>
-#endif
-
 #include <bson/bson-config.h>
 #include <bson/bson-macros.h>
 #include <bson/bson-compat.h>
@@ -36,12 +31,7 @@ BSON_BEGIN_DECLS
 #define BSON_BIG_ENDIAN 4321
 #define BSON_LITTLE_ENDIAN 1234
 
-
-#if defined(__sun)
-#define BSON_UINT16_SWAP_LE_BE(v) BSWAP_16 ((uint16_t) v)
-#define BSON_UINT32_SWAP_LE_BE(v) BSWAP_32 ((uint32_t) v)
-#define BSON_UINT64_SWAP_LE_BE(v) BSWAP_64 ((uint64_t) v)
-#elif defined(__clang__) && defined(__clang_major__) && defined(__clang_minor__) && (__clang_major__ >= 3) && \
+#if defined(__clang__) && defined(__clang_major__) && defined(__clang_minor__) && (__clang_major__ >= 3) && \
    (__clang_minor__ >= 1)
 #if __has_builtin(__builtin_bswap16)
 #define BSON_UINT16_SWAP_LE_BE(v) __builtin_bswap16 (v)
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-error.c b/src/third_party/libbson/dist/src/libbson/src/bson/bson-error.c
index 0c6257b1e21..3a42e44af3e 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-error.c
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-error.c
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-error.h b/src/third_party/libbson/dist/src/libbson/src/bson/bson-error.h
index 7d17b84cdcd..855af02bb19 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-error.h
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-error.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-iso8601-private.h b/src/third_party/libbson/dist/src/libbson/src/bson/bson-iso8601-private.h
index 81909a79102..b4c846fff44 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-iso8601-private.h
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-iso8601-private.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2014 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-iso8601.c b/src/third_party/libbson/dist/src/libbson/src/bson/bson-iso8601.c
index 47687cec24f..992ad91a455 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-iso8601.c
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-iso8601.c
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-iter.c b/src/third_party/libbson/dist/src/libbson/src/bson/bson-iter.c
index 0925b02c184..5159a39b518 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-iter.c
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-iter.c
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2014 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -62,6 +62,7 @@ bson_iter_init (bson_iter_t *iter,  /* OUT */
    iter->d4 = 0;
    iter->next_off = 4;
    iter->err_off = 0;
+   iter->value = (bson_value_t){0};
 
    return true;
 }
@@ -640,7 +641,7 @@ fill_data_fields:
          /* subtype 2 has a redundant length header in the data */
          memcpy (&binary_len, (iter->raw + iter->d3), sizeof (binary_len));
          binary_len = BSON_UINT32_FROM_LE (binary_len);
-         if (binary_len + 4 != l) {
+         if (binary_len != l - 4) {
             iter->err_off = iter->d3;
             goto mark_invalid;
          }
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-iter.h b/src/third_party/libbson/dist/src/libbson/src/bson/bson-iter.h
index 5370922d6d6..56bda8e8644 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-iter.h
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-iter.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-json-private.h b/src/third_party/libbson/dist/src/libbson/src/bson/bson-json-private.h
index 7a562a2b093..7537d6fc453 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-json-private.h
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-json-private.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2020 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-json.c b/src/third_party/libbson/dist/src/libbson/src/bson/bson-json.c
index 7d96104fe1d..5b53dd86a32 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-json.c
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-json.c
@@ -1,5 +1,5 @@
 /*
- * Copyright 2014 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-json.h b/src/third_party/libbson/dist/src/libbson/src/bson/bson-json.h
index 57f14a71969..68fbcb8ae96 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-json.h
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-json.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2014 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-keys.c b/src/third_party/libbson/dist/src/libbson/src/bson/bson-keys.c
index 9ba141c6ce4..7307664ce64 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-keys.c
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-keys.c
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,6 +19,7 @@
 
 #include <bson/bson-keys.h>
 #include <bson/bson-string.h>
+#include <bson/bson-cmp.h>
 
 
 static const char *gUint32Strs[] = {
@@ -141,5 +142,9 @@ bson_uint32_to_string (uint32_t value,      /* IN */
 
    *strptr = str;
 
-   return bson_snprintf (str, size, "%u", value);
+   int ret = bson_snprintf (str, size, "%u", value);
+   // Truncation is OK.
+   BSON_ASSERT (ret > 0);
+   BSON_ASSERT (bson_in_range_size_t_signed (ret));
+   return (size_t) ret;
 }
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-keys.h b/src/third_party/libbson/dist/src/libbson/src/bson/bson-keys.h
index 14f19f321b2..08f14e8ba38 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-keys.h
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-keys.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-macros.h b/src/third_party/libbson/dist/src/libbson/src/bson/bson-macros.h
index f9263914f1f..86c399db235 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-macros.h
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-macros.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -232,6 +232,10 @@
       }                                                                                              \
    } while (0)
 
+// `BSON_OPTIONAL_PARAM` is a documentation-only macro to document X may be NULL.
+// Useful in combination with `BSON_ASSERT_PARAM` to document and assert pointer parameters.
+#define BSON_OPTIONAL_PARAM(param) (void) 0
+
 /* obsolete macros, preserved for compatibility */
 #define BSON_STATIC_ASSERT(s) BSON_STATIC_ASSERT_ (s, __LINE__)
 #define BSON_STATIC_ASSERT_JOIN(a, b) BSON_STATIC_ASSERT_JOIN2 (a, b)
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-memory.c b/src/third_party/libbson/dist/src/libbson/src/bson/bson-memory.c
index 6c37003f2be..fbf7fbd2e60 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-memory.c
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-memory.c
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-memory.h b/src/third_party/libbson/dist/src/libbson/src/bson/bson-memory.h
index bde15edaef8..113b9ea14f2 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-memory.h
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-memory.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-oid.c b/src/third_party/libbson/dist/src/libbson/src/bson/bson-oid.c
index 090ac3eda8b..ae7d8910624 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-oid.c
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-oid.c
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-oid.h b/src/third_party/libbson/dist/src/libbson/src/bson/bson-oid.h
index 4829e28f5e4..d7d1585f9fc 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-oid.h
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-oid.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-prelude.h b/src/third_party/libbson/dist/src/libbson/src/bson/bson-prelude.h
index 2469125fe17..adbbf14c592 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-prelude.h
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-prelude.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2018-present MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-private.h b/src/third_party/libbson/dist/src/libbson/src/bson/bson-private.h
index 3b006a34796..92004805767 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-private.h
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-private.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-reader.c b/src/third_party/libbson/dist/src/libbson/src/bson/bson-reader.c
index 84ade059116..1d3feb7d9c4 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-reader.c
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-reader.c
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-reader.h b/src/third_party/libbson/dist/src/libbson/src/bson/bson-reader.h
index 827b0fe936b..3de90406650 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-reader.h
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-reader.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-string.c b/src/third_party/libbson/dist/src/libbson/src/bson/bson-string.c
index 85de12cb781..0ca48b70086 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-string.c
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-string.c
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -292,7 +292,7 @@ bson_string_append_printf (bson_string_t *string, const char *format, ...)
  *       Truncate the string @string to @len bytes.
  *
  *       The underlying memory will be released via realloc() down to
- *       the minimum required size specified by @len.
+ *       the minimum required size (at power-of-two boundary) specified by @len.
  *
  * Returns:
  *       None.
@@ -307,19 +307,17 @@ void
 bson_string_truncate (bson_string_t *string, /* IN */
                       uint32_t len)          /* IN */
 {
-   uint32_t alloc;
-
-   BSON_ASSERT (string);
-   BSON_ASSERT (len < INT_MAX);
-
-   alloc = len + 1;
-
-   if (alloc < 16) {
-      alloc = 16;
+   BSON_ASSERT_PARAM (string);
+   if (len == string->len) {
+      return;
    }
-
-   if (!bson_is_power_of_two (alloc)) {
-      alloc = (uint32_t) bson_next_power_of_two ((size_t) alloc);
+   uint32_t needed = len;
+   BSON_ASSERT (needed < UINT32_MAX);
+   needed += 1u; // Add one for trailing NULL byte.
+   uint32_t alloc = bson_next_power_of_two_u32 (needed);
+   if (alloc == 0) {
+      // Overflowed: saturate at UINT32_MAX.
+      alloc = UINT32_MAX;
    }
 
    string->str = bson_realloc (string->str, alloc);
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-string.h b/src/third_party/libbson/dist/src/libbson/src/bson/bson-string.h
index 3759afff0bd..4146ebaa2bf 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-string.h
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-string.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-timegm-private.h b/src/third_party/libbson/dist/src/libbson/src/bson/bson-timegm-private.h
index 93d9a8e7216..0490d012a83 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-timegm-private.h
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-timegm-private.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2014 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-types.h b/src/third_party/libbson/dist/src/libbson/src/bson/bson-types.h
index 31486687396..135b60f833f 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-types.h
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-types.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-utf8.c b/src/third_party/libbson/dist/src/libbson/src/bson/bson-utf8.c
index 61fa98598ed..b39da8f5448 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-utf8.c
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-utf8.c
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -278,6 +278,15 @@ bson_utf8_escape_for_json (const char *utf8, /* IN */
    end = utf8 + utf8_len;
 
    while (utf8 < end) {
+      uint8_t mask;
+      uint8_t length_of_char;
+
+      // Check if expected char length goes past end
+      _bson_utf8_get_sequence (utf8, &length_of_char, &mask);
+      if (utf8 > end - length_of_char) {
+         goto invalid_utf8;
+      }
+
       c = bson_utf8_get_char (utf8);
 
       switch (c) {
@@ -313,18 +322,25 @@ bson_utf8_escape_for_json (const char *utf8, /* IN */
       if (c) {
          utf8 = bson_utf8_next_char (utf8);
       } else {
-         if (length_provided && !*utf8) {
-            /* we escaped nil as '\u0000', now advance past it */
-            utf8++;
+         if (length_provided) {
+            // Check if current character is null character,
+            // if so skip past it as we've already added '\\u0000' above
+            if (*utf8 == '\0' || (*utf8 == '\xc0' && *(utf8 + 1) == '\x80')) {
+               utf8 += (*utf8 == '\0') ? 1 : 2;
+            } else {
+               goto invalid_utf8;
+            }
          } else {
-            /* invalid UTF-8 */
-            bson_string_free (str, true);
-            return NULL;
+            goto invalid_utf8;
          }
       }
    }
 
    return bson_string_free (str, false);
+
+invalid_utf8:
+   bson_string_free (str, true);
+   return NULL;
 }
 
 
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-utf8.h b/src/third_party/libbson/dist/src/libbson/src/bson/bson-utf8.h
index af085969412..fc58d3c5a72 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-utf8.h
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-utf8.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-value.c b/src/third_party/libbson/dist/src/libbson/src/bson/bson-value.c
index 3e3c46890db..a8aabd3344b 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-value.c
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-value.c
@@ -1,5 +1,5 @@
 /*
- * Copyright 2014 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,6 +19,7 @@
 #include <bson/bson-string.h>
 #include <bson/bson-value.h>
 #include <bson/bson-oid.h>
+#include <bson/bson-cmp.h>
 
 
 void
@@ -35,8 +36,11 @@ bson_value_copy (const bson_value_t *src, /* IN */
       dst->value.v_double = src->value.v_double;
       break;
    case BSON_TYPE_UTF8:
+      BSON_ASSERT (bson_in_range_size_t_unsigned (src->value.v_utf8.len));
+      size_t utf8_len_sz = (size_t) src->value.v_utf8.len;
+      BSON_ASSERT (utf8_len_sz <= SIZE_MAX - 1);
       dst->value.v_utf8.len = src->value.v_utf8.len;
-      dst->value.v_utf8.str = bson_malloc (src->value.v_utf8.len + 1);
+      dst->value.v_utf8.str = bson_malloc (utf8_len_sz + 1);
       memcpy (dst->value.v_utf8.str, src->value.v_utf8.str, dst->value.v_utf8.len);
       dst->value.v_utf8.str[dst->value.v_utf8.len] = '\0';
       break;
@@ -68,28 +72,40 @@ bson_value_copy (const bson_value_t *src, /* IN */
       dst->value.v_regex.options = bson_strdup (src->value.v_regex.options);
       break;
    case BSON_TYPE_DBPOINTER:
+      BSON_ASSERT (bson_in_range_size_t_unsigned (src->value.v_dbpointer.collection_len));
+      size_t dbpointer_len_sz = (size_t) src->value.v_dbpointer.collection_len;
+      BSON_ASSERT (dbpointer_len_sz <= SIZE_MAX - 1);
       dst->value.v_dbpointer.collection_len = src->value.v_dbpointer.collection_len;
-      dst->value.v_dbpointer.collection = bson_malloc (src->value.v_dbpointer.collection_len + 1);
+      dst->value.v_dbpointer.collection = bson_malloc (dbpointer_len_sz + 1);
       memcpy (
          dst->value.v_dbpointer.collection, src->value.v_dbpointer.collection, dst->value.v_dbpointer.collection_len);
       dst->value.v_dbpointer.collection[dst->value.v_dbpointer.collection_len] = '\0';
       bson_oid_copy (&src->value.v_dbpointer.oid, &dst->value.v_dbpointer.oid);
       break;
    case BSON_TYPE_CODE:
+      BSON_ASSERT (bson_in_range_size_t_unsigned (src->value.v_code.code_len));
+      size_t code_len_sz = (size_t) src->value.v_code.code_len;
+      BSON_ASSERT (code_len_sz <= SIZE_MAX - 1);
       dst->value.v_code.code_len = src->value.v_code.code_len;
-      dst->value.v_code.code = bson_malloc (src->value.v_code.code_len + 1);
+      dst->value.v_code.code = bson_malloc (code_len_sz + 1);
       memcpy (dst->value.v_code.code, src->value.v_code.code, dst->value.v_code.code_len);
       dst->value.v_code.code[dst->value.v_code.code_len] = '\0';
       break;
    case BSON_TYPE_SYMBOL:
+      BSON_ASSERT (bson_in_range_size_t_unsigned (src->value.v_symbol.len));
+      size_t symbol_len_sz = (size_t) src->value.v_symbol.len;
+      BSON_ASSERT (symbol_len_sz <= SIZE_MAX - 1);
       dst->value.v_symbol.len = src->value.v_symbol.len;
-      dst->value.v_symbol.symbol = bson_malloc (src->value.v_symbol.len + 1);
+      dst->value.v_symbol.symbol = bson_malloc (symbol_len_sz + 1);
       memcpy (dst->value.v_symbol.symbol, src->value.v_symbol.symbol, dst->value.v_symbol.len);
       dst->value.v_symbol.symbol[dst->value.v_symbol.len] = '\0';
       break;
    case BSON_TYPE_CODEWSCOPE:
+      BSON_ASSERT (bson_in_range_size_t_unsigned (src->value.v_codewscope.code_len));
+      size_t codewscope_len_sz = (size_t) src->value.v_codewscope.code_len;
+      BSON_ASSERT (codewscope_len_sz <= SIZE_MAX - 1);
       dst->value.v_codewscope.code_len = src->value.v_codewscope.code_len;
-      dst->value.v_codewscope.code = bson_malloc (src->value.v_codewscope.code_len + 1);
+      dst->value.v_codewscope.code = bson_malloc (codewscope_len_sz + 1);
       memcpy (dst->value.v_codewscope.code, src->value.v_codewscope.code, dst->value.v_codewscope.code_len);
       dst->value.v_codewscope.code[dst->value.v_codewscope.code_len] = '\0';
       dst->value.v_codewscope.scope_len = src->value.v_codewscope.scope_len;
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-value.h b/src/third_party/libbson/dist/src/libbson/src/bson/bson-value.h
index 41756907df0..afb11a5006b 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-value.h
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-value.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2014 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-version-functions.c b/src/third_party/libbson/dist/src/libbson/src/bson/bson-version-functions.c
index 90406edb366..55de41026c9 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-version-functions.c
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-version-functions.c
@@ -1,5 +1,5 @@
 /*
- * Copyright 2015 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-version-functions.h b/src/third_party/libbson/dist/src/libbson/src/bson/bson-version-functions.h
index 923dcf0dc60..e97376a57d2 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-version-functions.h
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-version-functions.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2015 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-version.h.in b/src/third_party/libbson/dist/src/libbson/src/bson/bson-version.h.in
index 618369995dc..4d9fcac4893 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-version.h.in
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-version.h.in
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-writer.c b/src/third_party/libbson/dist/src/libbson/src/bson/bson-writer.c
index d547698aea5..40721eb5498 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-writer.c
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-writer.c
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson-writer.h b/src/third_party/libbson/dist/src/libbson/src/bson/bson-writer.h
index dd7d8988c9c..37e8c26c16d 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson-writer.h
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson-writer.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson.c b/src/third_party/libbson/dist/src/libbson/src/bson/bson.c
index e29b2a771cc..5b91bec86af 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson.c
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson.c
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -3299,29 +3299,35 @@ _bson_validate_internal (const bson_t *bson, bson_validate_state_t *state)
 bool
 bson_validate (const bson_t *bson, bson_validate_flags_t flags, size_t *offset)
 {
-   bson_validate_state_t state;
-
-   state.flags = flags;
-   _bson_validate_internal (bson, &state);
-
-   if (state.err_offset > 0 && offset) {
-      *offset = (size_t) state.err_offset;
-   }
-
-   return state.err_offset < 0;
+   return bson_validate_with_error_and_offset (bson, flags, offset, NULL);
 }
 
 
 bool
 bson_validate_with_error (const bson_t *bson, bson_validate_flags_t flags, bson_error_t *error)
+{
+   return bson_validate_with_error_and_offset (bson, flags, NULL, error);
+}
+
+
+bool
+bson_validate_with_error_and_offset (const bson_t *bson,
+                                     bson_validate_flags_t flags,
+                                     size_t *offset,
+                                     bson_error_t *error)
 {
    bson_validate_state_t state;
 
    state.flags = flags;
    _bson_validate_internal (bson, &state);
 
-   if (state.err_offset > 0 && error) {
-      memcpy (error, &state.error, sizeof *error);
+   if (state.err_offset > 0) {
+      if (offset) {
+         *offset = (size_t) state.err_offset;
+      }
+      if (error) {
+         memcpy (error, &state.error, sizeof *error);
+      }
    }
 
    return state.err_offset < 0;
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/bson.h b/src/third_party/libbson/dist/src/libbson/src/bson/bson.h
index f86967bae1f..f66b5a1297c 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/bson.h
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/bson.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -454,6 +454,25 @@ BSON_EXPORT (bool)
 bson_validate_with_error (const bson_t *bson, bson_validate_flags_t flags, bson_error_t *error);
 
 
+/**
+ * bson_validate_with_error_and_offset:
+ * @bson: A bson_t.
+ * @offset: A location for the error offset.
+ * @error: A location for the error info.
+ *
+ * Validates a BSON document by walking through the document and inspecting
+ * the fields for valid content.
+ *
+ * Returns: true if @bson is valid; otherwise false, @offset is set
+ * and @error is filled out.
+ */
+BSON_EXPORT (bool)
+bson_validate_with_error_and_offset (const bson_t *bson,
+                                     bson_validate_flags_t flags,
+                                     size_t *offset,
+                                     bson_error_t *error);
+
+
 /**
  * bson_as_json_with_opts:
  * @bson: A bson_t.
diff --git a/src/third_party/libbson/dist/src/libbson/src/bson/forwarding/bson.h b/src/third_party/libbson/dist/src/libbson/src/bson/forwarding/bson.h
index cfe6d0682f3..e8ae7264a03 100644
--- a/src/third_party/libbson/dist/src/libbson/src/bson/forwarding/bson.h
+++ b/src/third_party/libbson/dist/src/libbson/src/bson/forwarding/bson.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2018-present MongoDB, Inc.
+ * Copyright 2009-present MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -15,4 +15,4 @@
  */
 
 /* Including bson.h is superseded. Use bson/bson.h instead. */
-#include "bson/bson.h"
\ No newline at end of file
+#include "bson/bson.h"
diff --git a/src/third_party/libbson/import.sh b/src/third_party/libbson/import.sh
index d48aa0c5e9e..1bbea64a2c7 100755
--- a/src/third_party/libbson/import.sh
+++ b/src/third_party/libbson/import.sh
@@ -18,7 +18,7 @@ if grep -q Microsoft /proc/version; then
 fi
 
 NAME=libbson
-VERSION=1.27.6
+VERSION=1.28.1
 
 if grep -q Microsoft /proc/version; then
     SRC_ROOT=$(wslpath -u $(powershell.exe -Command "Get-ChildItem Env:TEMP | Get-Content | Write-Host"))