Vulnerability in jpadilla pyjwt

[ Why it matters ]Priority signals

• Public proof-of-concept exploit exists (CISA SSVC)

[ Description ]Official description

PyJWT is a JSON Web Token implementation in Python. Prior to 2.12.0, PyJWT does not validate the crit (Critical) Header Parameter defined in RFC 7515 §4.1.11. When a JWS token contains a crit array listing extensions that PyJWT does not understand, the library accepts the token instead of rejecting it. This violates the MUST requirement in the RFC. This vulnerability is fixed in 2.12.0.

[ Fixes ]Fixes and patches

No fix or interim patch is linked from our sources yet. Check the vendor references below and limit exposure of affected systems until a fix is available.

[ Advisories ]Government CERT advisories

• BSI CERT-Bund1 Nov 2026WID-SEC-2026-4264

  Red Hat Enterprise Linux (PyJWT): Vulnerability allows bypassing security measures Translated from German

  CVE-2026-32597
• CERT-FR9 Oct 2026CERTFR-2026-AVI-1291

  Multiple vulnerabilities in IBM products Translated from French

  Multiple vulnerabilities have been discovered in IBM products. Some of them allow an attacker to cause remote arbitrary code execution, privilege escalation and remote denial of service.

  CVE-2026-49978CVE-2025-27895CVE-2026-59651+195 more CVEs

[ References ]References

• github.com/jpadilla/pyjwt/security/advisories/GHSA-752w-5fwx-jx9fx_refsource_CONFIRM