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Update security docs

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- docs/handbook/security.rst
- .github/SECURITY.md

Co-authored-by: Andrew Murray <3112309+radarhere@users.noreply.github.com>
This commit is contained in:
Jeffrey 'Alex' Clark 2026-04-15 13:03:19 -04:00
parent b300e78838
commit 0c0bdf8d5a
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To report sensitive vulnerability information, report it [privately on GitHub](https://github.com/python-pillow/Pillow/security/advisories/new).
If you cannot use GitHub, use the [Tidelift security contact](https://tidelift.com/security). Tidelift will coordinate the fix and disclosure.
If you cannot use GitHub, use the [Tidelift security contact](https://tidelift.com/docs/security). Tidelift will coordinate the fix and disclosure.
**DO NOT report sensitive vulnerability information in public.**
## Threat model
Pillow's primary attack surface is parsing untrusted image data. A full STRIDE threat model covering spoofing, tampering, repudiation, information disclosure, denial of service, and elevation of privilege is maintained in the [Security handbook page](https://pillow.readthedocs.io/en/stable/handbook/security.html).
Pillow's primary attack surface is parsing untrusted image data. A full STRIDE threat model covering spoofing, tampering, repudiation, information disclosure, denial of service, and elevation of privilege is maintained in the [Security handbook page](https://pillow.readthedocs.io/en/latest/handbook/security.html).
Key risks to be aware of when using Pillow to process untrusted images:

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A small compressed image can expand to gigabytes in memory.
:py:data:`PIL.Image.MAX_IMAGE_PIXELS` raises
``DecompressionBombError`` at 2× the limit and
``DecompressionBombWarning`` at 1×. PNG text chunks are
``Image.DecompressionBombError`` at 2× the limit and
``Image.DecompressionBombWarning`` at 1×. PNG text chunks are
separately capped by ``PngImagePlugin.MAX_TEXT_CHUNK`` and
``MAX_TEXT_MEMORY``. Check the values in your installed Pillow version at
runtime or in the reference/source for the current defaults.
*Mitigations:* **never** set ``Image.MAX_IMAGE_PIXELS = None`` in production;
treat ``DecompressionBombWarning`` as an error; set OS/container memory limits
treat ``Image.DecompressionBombWarning`` as an error; set OS/container memory limits
per worker.
**D-2 — CPU exhaustion**
@ -234,7 +234,7 @@ The following mitigations are listed in priority order.
libwebp, openjpeg, freetype, Ghostscript. Subscribe to `Pillow security
advisories <https://github.com/python-pillow/Pillow/security/advisories>`_.
5. **Enforce** ``MAX_IMAGE_PIXELS`` — never set it to ``None``; treat
``DecompressionBombWarning`` as an error.
``Image.DecompressionBombWarning`` as an error.
6. **Allowlist image formats** — unregister plugins your application does not
need.
7. **Strip metadata on output** — never pass through EXIF/XMP/ICC from user
@ -242,8 +242,8 @@ The following mitigations are listed in priority order.
8. **Sanitise all metadata** returned by Pillow before using it downstream.
9. **Pin dependencies with hash verification** — use
``pip install --require-hashes`` and lockfiles.
10. **Log and alert** on ``DecompressionBombWarning``,
``DecompressionBombError``, ``PIL.UnidentifiedImageError``,
10. **Log and alert** on ``Image.DecompressionBombWarning``,
``Image.DecompressionBombError``, ``PIL.UnidentifiedImageError``,
and all exceptions from ``Image.open()``.
.. _security-reporting:
@ -255,7 +255,7 @@ To report sensitive vulnerability information, report it `privately on GitHub
<https://github.com/python-pillow/Pillow/security/advisories/new>`_.
If you cannot use GitHub, use the `Tidelift security contact
<https://tidelift.com/security>`_. Tidelift will coordinate the fix and
<https://tidelift.com/docs/security>`_. Tidelift will coordinate the fix and
disclosure.
**Do not report sensitive vulnerability information in public.**