GitHub Advisoryadvisory · PyPI

GHSA-9mvc-8737-8j8h pypdf possibly has long runtimes for malformed FlateDecode streams

MEDIUM Published 2026-02-18 Modified 2026-02-23 Official page ↗
Aliases
CVE-2026-27026
Ecosystem
PyPI
Packages
pypdf
Severity
Moderate
CVSS vector
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Weaknesses
CWE-770
Reviewed
2026-02-18

Affected packages

• PyPI pypdf: < 6.7.1 → fixed in 6.7.1

Description

Impact 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. Patches This has been fixed in pypdf==6.7.1. Workarounds If you cannot upgrade yet, consider applying the changes from PR #3644.

Related

Alias · CVE (1)

  • CVE-2026-27026 pypdf is a free and open-source pure-python PDF library. vulnerability

Weakness · CWE (1)

  • CWE-770 Allocation of Resources Without Limits or Throttling weakness

References