by Kastro
Paper/Archive/CVE-2026-96639

CVE-2026-96639

python-pillow Pillow — Pillow multi-frame loaders can reuse stale native image storage after mode transitions

EPSS 0.7%CVSS 9.8
critical.is priorityof 100
40
CVSS 9.8 (CNA)9.8 / 10 × 3029.4Not in CISA KEV+300.0EPSS percentile 51.4.514 × 2010.3No public exploit+100.0SSVC exploitation: none+100.0
Description · from the CVE record

Pillow is a Python imaging library. From 11.0.0 until 13.0.0, multi-frame loaders can retain an ImagingCore allocation created for a narrow frame mode while a later frame of the same dimensions changes the logical mode and decoder tiles to wider RGB or CMYK data. ImageFile.load_prepare() reuses the stale native storage because _im is non-null without verifying that its mode and size still match. Crafted PSD, MPO, DCX, or MIC frame transitions can then write wider pixels into the narrow allocation, causing native out-of-bounds writes and crashes. The MPO path can also cause a native over-read and, in demonstrated runtime-specific profiles, command execution. This issue is fixed in version 13.0.0.

Affected

ProductAffectedFixed inSource
Pillow>= 11.0.0, < 13.0.0–CNA

Scores by source

GitHub_M (CNA)9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CISA ADPSSVCExploitation: none · Automatable: yes · Technical impact: total

References

refgithub.com/python-pillow/Pillow/security/advisories/GHSA-v9pv-5gc8-w2m6refgithub.com/python-pillow/Pillow/pull/10105refgithub.com/python-pillow/Pillow/commit/78d97d994579aef81aafe123773d525f40f2522arefgithub.com/python-pillow/Pillow/releases/tag/13.0.0