CVE-2026-27026: 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 6.7.1, an attacker who uses this vulnerability can craft a PDF which leads to long runtimes. This requires a malformed /FlateDecode stream, where the byte-by-byte decompression is used. This vulnerability is fixed in 6.7.1.

Affected products

• Pypdf Project Pypdf: before 6.7.1 (fixed in 6.7.1)

Published 2026-02-20. Last modified 2026-06-17.