py-pdf/pypdf · Security
pypdf possibly has long runtimes for malformed FlateDecode streams
- GHSA ID
- GHSA-9mvc-8737-8j8h
- CVE ID
- CVE-2026-27026
- Severity
- medium
- Published
- Updated
- CVSS v4
- 6.9 · 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
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.
CWEs
- CWE-770 · Allocation of Resources Without Limits or Throttling
References
- https://github.com/py-pdf/pypdf/security/advisories/GHSA-9mvc-8737-8j8h ↗
- https://github.com/py-pdf/pypdf/pull/3644 ↗
- https://github.com/py-pdf/pypdf/commit/7905842d833f899f1d3228af7e7467ad80277016 ↗
- https://github.com/py-pdf/pypdf/releases/tag/6.7.1 ↗
- https://nvd.nist.gov/vuln/detail/CVE-2026-27026 ↗
- https://github.com/advisories/GHSA-9mvc-8737-8j8h ↗