CVE-2026-22691: Pypdf Project Pypdf

Medium severity, CVSS 5.3. EPSS: 0.4% chance of exploitation in the next 30 days.

pypdf is a free and open-source pure-python PDF library. Prior to version 6.6.0, pypdf has possible long runtimes for malformed startxref. An attacker who uses this vulnerability can craft a PDF which leads to possibly long runtimes for invalid startxref entries. When rebuilding the cross-reference table, PDF files with lots of whitespace characters become problematic. Only the non-strict reading mode is affected. Only the non-strict reading mode is affected. This issue has been patched in version 6.6.0.

Affected products

• Pypdf Project Pypdf: before 6.6.0 (fixed in 6.6.0)

Published 2026-01-10. Last modified 2026-06-17.