CVE-2026-54651: Pypdf Project Pypdf

Medium severity, CVSS 5.5. EPSS: 0.2% chance of exploitation in the next 30 days.

pypdf is a free and open-source pure-python PDF library. Prior to 6.13.1, an attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires merging a file with threads/articles into a writer. This vulnerability is fixed in 6.13.1.

Affected products

• Pypdf Project Pypdf: before 6.13.1 (fixed in 6.13.1)

Published 2026-06-22. Last modified 2026-06-24.