CVE-2026-102997: Pypdf Project Pypdf

High severity, CVSS 7.5. EPSS: 0.3% chance of exploitation in the next 30 days.

pypdf is a free and open-source pure-python PDF library. Prior to 6.18.1, a crafted PDF containing a partially malformed /FlateDecode stream with padded data can force pypdf/filters.py to use inefficient byte-by-byte decompression while the earlier recovery counter fails to advance for bytes that successfully decode, causing long runtimes and application unavailability. This is a residual issue after the malformed FlateDecode recovery fix. This issue is fixed in version 6.18.1.

Affected products

• Pypdf Project Pypdf: before 6.18.1 (fixed in 6.18.1)

Published 2026-09-30. Last modified 2026-10-05.