CVE-2026-42308: Pillow: Integer overflow when processing fonts

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-05-09 · updated 2026-07-24
Weakness: CWE-190

Description

Pillow is a Python imaging library. Prior to version 12.2.0, if a font advances for each glyph by an exceeding large amount, when Pillow keeps track of the current position, it may lead to an integer overflow. This issue has been patched in version 12.2.0.

Affected products

python-pillow Pillow: before 12.2.0 — fixed in 12.2.0
Pypi Pillow: before 12.2.0; 1.0, 1.1, 1.2, 1.3, 1.4, 1.5 (+99) — fixed in 12.2.0

How to fix

Upgrade to a fixed version: python-pillow Pillow 12.2.0; Pypi Pillow 12.2.0. Check the vendor advisory for mitigations.

References

https://github.com/python-pillow/Pillow/releases/tag/12.2.0
https://github.com/python-pillow/Pillow/security/advisories/GHSA-wjx4-4jcj-g98j

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