PT-2026-59511 · Pypi · Pillow

Published 2026-07-13 · Updated 2026-07-13

OSV

CVSS v3.1

5.5

Medium

Base vector

AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Impact

An attacker can supply a malicious PDF that causes the process to hang indefinitely, consuming 100% CPU and making the application unresponsive.

Patches

Patched version: 12.2.0.

PdfParser (introduced in Pillow 4.2.0) follows Prev pointers in PDF trailers to read cross-reference sections. If a trailer's Prev pointer references an offset that has already been processed — either pointing to itself or forming a longer cycle — the parser enters an infinite loop. Pillow now tracks previously processed trailer offsets and raises an error if a cycle is detected.

Workarounds

Use any version but the affected versions: >= 4.2.0, < 12.2.0

Resources

• Fix: https://github.com/python-pillow/Pillow/pull/9519

Fix

Related Identifiers

PYSEC-2026-2874

Affected Products

Pillow

References · 9

• https://osv.dev/vulnerability/PYSEC-2026-2874 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-42310 · Security Note
• https://github.com/python-pillow/Pillow/commit/3bf614e4b8615d0ce1d5039efaf6db447fe7c468 · Note
• https://github.com/python-pillow/Pillow/pull/9519 · Note
• https://github.com/python-pillow/Pillow/releases/tag/12.2.0 · Note
• https://github.com/python-pillow/Pillow/security/advisories/GHSA-r73j-pqj5-w3x7 · Note
• https://github.com/python-pillow/Pillow · Note
• https://pypi.org/project/pillow · Note
• https://github.com/advisories/GHSA-r73j-pqj5-w3x7 · Note