Out-of-bounds Read in Python-Pillow Pillow
CVE-2026-96639
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.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
- Python-Pillow Pillow — versions >= 11.0.0, < 13.0.0
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-96639?
- CVE-2026-96639 is a critical-severity vulnerability in Python-Pillow Pillow, classified under Out-of-bounds Read. CVSS score: 9.8/10. Published 2026-10-21.
- How severe is CVE-2026-96639?
- Critical severity. CVSS v3 base score is 9.8 out of 10.