Pillow is a Python imaging library. From 5.1.0 until 12.3.0, PdfParser.PdfStream.decode() in PIL/PdfParser.py calls zlib.decompress() with bufsize set to the PDF stream Length field without bounding the decompressed output size, allowing a crafted FlateDecode PDF stream to exhaust memory from a small file. This issue is fixed in version 12.3.0.
Fix
Patch, vendor advisory and mitigation references on NVD 4
- https://github.com/python-pillow/Pillow/commit/f7a31ea75e460e108c37126da1f47812f21f6b09 Patch
- https://github.com/python-pillow/Pillow/pull/9718 Issue Tracking, Patch
- https://github.com/python-pillow/Pillow/security/advisories/GHSA-jjj6-mw9f-p565 Exploit, Vendor Advisory
- https://github.com/python-pillow/Pillow/security/advisories/GHSA-jjj6-mw9f-p565 Exploit, Vendor Advisory
Every line above is quoted from NVD, CISA, Microsoft, the vendor's own advisory or DISA; nothing is generated.
Change history 1
- First seenCVSS 7.5 · pythonNVD modified 2026-10-24 21:10
Affected (CPE criteria) 1
cpe:2.3:a:python:pillow:*:*:*:*:*:*:*:*
References 5
- https://github.com/python-pillow/Pillow/commit/f7a31ea75e460e108c37126da1f47812f21f6b09 Patch
- https://github.com/python-pillow/Pillow/pull/9718 Issue Tracking, Patch
- https://github.com/python-pillow/Pillow/releases/tag/12.3.0 Release Notes
- https://github.com/python-pillow/Pillow/security/advisories/GHSA-jjj6-mw9f-p565 Exploit, Vendor Advisory
- https://github.com/python-pillow/Pillow/security/advisories/GHSA-jjj6-mw9f-p565 Exploit, Vendor Advisory