CVE-2026-82398: Pypdf Project Pypdf

Medium severity, CVSS 5.3. EPSS: 0.5% chance of exploitation in the next 30 days.

pypdf is a free and open-source pure-python PDF library. Prior to 6.15.0, an attacker can craft a PDF that causes long runtimes when the pypdf/_utils.py function read_until_whitespace reads a stream containing a long run of bytes without whitespace. The function repeatedly performs immutable bytes concatenation in a one-byte loop, causing quadratic processing cost for the long non-whitespace input. This issue is fixed in version 6.15.0.

Affected products

• Pypdf Project Pypdf: before 6.15.0 (fixed in 6.15.0)

Published 2026-08-31. Last modified 2026-10-05.