CVE-2026-96639 Pillow multi-frame loaders can reuse stale native image storage after mode transitions

What is CVE-2026-96639?

CVE-2026-96639 is a critical vulnerability in Python Pillow, published on 21 Oct 2026.

Official description

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.

Weakness: CWE-787, CWE-125

Which versions are affected by CVE-2026-96639?

4 open source packages ship an affected version, including pillow and Pillow. It affects 1 product.

Products include Python Pillow.

How do I fix CVE-2026-96639?

Upgrade pillow to 13.0.0 or later.

Is CVE-2026-96639 being exploited?

There is no known exploitation of CVE-2026-96639 in the wild and no public exploit code.

Other vulnerabilities in Python Pillow

• CVE-2014-3007 Pillow command injection Critical 10.0
• CVE-2022-30595 Buffer over-flow in Pillow Critical 9.8
• CVE-2021-25289 Out of bounds write in Pillow Critical 9.8
• CVE-2016-4009 Pillow Integer overflow in ImagingResampleHorizontal Critical 9.8
• CVE-2026-112393 Pillow: Heap buffer overflow in _tiffWriteProc when saving TIFF to BytesIO Critical 9.2

All Python Pillow vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BIT-pillow-2026-96639, DEBIAN-CVE-2026-96639, ECHO-68a5-bb35-54de, GHSA-v9pv-5gc8-w2m6, PYSEC-2026-4339, ROOT-APP-PYPI-CVE-2026-96639 and 1 more.