CVE-2026-112398: Pillow: Heap buffer overflow in FlashPix (FPX) JPEG decoding leads to code execution

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-10-19 · updated 2026-10-27
Weakness: CWE-122

Description

Pillow is a Python imaging library. Prior to 13.0.0, Pillow's FlashPix JPEG-tile decoder can write decoded scanlines beyond the allocated tile buffer. FlashPix (FPX) JPEG decoding selects raw mode LA with two bytes per pixel, while an unrecognized JPEG mode can be decoded as JCS_UNKNOWN with four components, causing ImagingJpegDecode to write four-component scanlines into the two-byte tile buffer. An attacker can supply a crafted OLE2 FlashPix file to an application with the optional olefile dependency installed that opens or thumbnails untrusted input. This can corrupt heap memory and may allow arbitrary code execution. This issue is fixed in version 13.0.0.

Affected products

python-pillow Pillow: before 13.0.0 — fixed in 13.0.0
Pypi Pillow: before 13.0.0; 1.0, 1.1, 1.2, 1.3, 1.4, 1.5 (+101) — fixed in 13.0.0
python-pillow Pillow: before 13.0.0

How to fix

Upgrade to a fixed version: python-pillow Pillow 13.0.0; Pypi Pillow 13.0.0. Check the vendor advisory for mitigations.

References

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