Pillow is a Python imaging library. Prior to 13.0.0, PILfont text-width accumulation in src/_imaging.c checks positive glyph advances against INT_MAX but does not check negative advances against INT_MIN. Repeating a signed 16-bit advance of -32768 can therefore execute a signed C integer overflow in xsize += dx, producing a large positive width from a negative mathematical result. Applications that use getlength(), getsize(), or derived layout, quota, serialization, or allocation calculations can experience logic-integrity errors or resource consumption, while the high-level mask path commonly retains a decompression-bomb check. This issue is fixed in version 13.0.0.
Fix
Patch, vendor advisory and mitigation references on NVD 2
- https://github.com/python-pillow/Pillow/commit/80de4be9e38d3a6148dd4d8491eb80cd12b760a4 Patch
- https://github.com/python-pillow/Pillow/security/advisories/GHSA-4rm8-3hmm-39fg Vendor Advisory
Every line above is quoted from NVD, CISA, Microsoft, the vendor's own advisory or DISA; nothing is generated.
Change history 6
- Cpes+1 CPE criteria (now 1)NVD modified 2026-10-27 14:26
- StatusAwaiting Analysis → AnalyzedNVD modified 2026-10-27 14:26
- StatusPublished → Awaiting AnalysisNVD modified 2026-10-22 16:46
- StatusReceived → PublishedNVD modified 2026-10-21 20:51
- StatusPublished → ReceivedNVD modified 2026-10-21 21:20
- First seenCVSS 6.5 · python-pillowNVD modified 2026-10-21 20:51
Affected (CPE criteria) 1
cpe:2.3:a:python:pillow:*:*:*:*:*:*:*:*
References 4
- https://github.com/python-pillow/Pillow/commit/80de4be9e38d3a6148dd4d8491eb80cd12b760a4 Patch
- https://github.com/python-pillow/Pillow/pull/10010 Issue Tracking
- https://github.com/python-pillow/Pillow/releases/tag/13.0.0 Release Notes
- https://github.com/python-pillow/Pillow/security/advisories/GHSA-4rm8-3hmm-39fg Vendor Advisory