CVE-2026-33123: Pypdf Project Pypdf

Medium severity, CVSS 6.5. EPSS: 0.4% chance of exploitation in the next 30 days.

pypdf is a free and open-source pure-python PDF library. Versions prior to 6.9.1 allow an attacker to craft a malicious PDF which leads to long runtimes and/or large memory usage. Exploitation requires accessing an array-based stream with many entries. This issue has been fixed in version 6.9.1.

Affected products

• Pypdf Project Pypdf: before 6.9.1 (fixed in 6.9.1)

Published 2026-03-20. Last modified 2026-06-17.