Package vulnerability, severity high

pypdf has possible infinite loop when cloning dictionaries

Published October 30, 2026, updated October 31, 2026

pypdf has possible infinite loop when cloning dictionaries. Source: GHSA-mfr5-77xh-9j7h (CVE-2026-119205).

What's affected

• pypdf (pypi)<6.21.4

What to do

1. Upgrade pypdf to 6.21.4 or later.

Check whether you were affected

Pharon tells teams automatically when this affects something they run. To check a machine, run this in Claude Code with the Pharon plugin, in the repository that uses it:

/pharon:check-incident ghsa-mfr5-77xh-9j7h

References

• https://osv.dev/vulnerability/GHSA-mfr5-77xh-9j7h
• https://github.com/py-pdf/pypdf/security/advisories/GHSA-mfr5-77xh-9j7h
• https://nvd.nist.gov/vuln/detail/CVE-2026-119205
• https://github.com/py-pdf/pypdf/pull/4288
• https://github.com/py-pdf/pypdf/commit/f176db1a1f7f9af3e472e69a843ef1175653b044
• https://github.com/py-pdf/pypdf
• https://github.com/py-pdf/pypdf/releases/tag/6.21.4

Notice ghsa-mfr5-77xh-9j7h, signed with key feed-prod-2026-10 (Ed25519). The Pharon CLI verifies the signature before using a notice.