PyJWT BOM Bypass

[ Why it matters ]Priority signals

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

[ Description ]Official description

PyJWT is a Python implementation of JSON Web Token standards. From 2.13.0 until 2.14.0, HMACAlgorithm.prepare_key in jwt/algorithms.py is affected because raw-JWK detector does not normalize accepted Unicode byte-order marks before checking for JSON. This occurs when a public JWK is prefixed with a UTF-8 BOM and used in a mixed-algorithm verification path. As a result, public JWK bypasses asymmetric-key detection and becomes the HMAC secret. Consequently, an attacker who knows the public key can forge authenticated tokens. This issue is fixed in version 2.14.0.

[ Fixes ]Fixes and patches

• PyJWT 2.14.0Fixed version · GitHub Advisories · pip package PyJWT: upgrade to 2.14.0 or later (affected = 2.13.0)
• Patch on github.comVendor patch or bulletin · NVD · Reference tagged 'Patch' by NVD

[ Advisories ]Government CERT advisories

• BSI CERT-Bund21 Oct 2026WID-SEC-2026-4111

  Red Hat Ansible Automation Platform: Multiple vulnerabilities Translated from German

  Risk highCVE-2026-11332CVE-2026-102938CVE-2026-103262+21 more CVEs
• CERT-FR2 Oct 2026CERTFR-2026-AVI-1249

  Multiple vulnerabilities in VMware products Translated from French

  Multiple vulnerabilities have been discovered in VMware products. They allow an attacker to cause a security problem not specified by the vendor.

  CVE-2026-75595CVE-2026-53910CVE-2026-56404+288 more CVEs

[ Packages ]Affected open-source packages

• PyJWT pipAffected = 2.13.0 · fixed in 2.14.0 · GHSA-r6x4-923q-g947

[ References ]References

• github.com/jpadilla/pyjwt/commit/180783930de91876bc0d601f826a1f2956057291Patch
• github.com/jpadilla/pyjwt/releases/tag/2.14.0ProductRelease Notes
• github.com/jpadilla/pyjwt/security/advisories/GHSA-r6x4-923q-g947ExploitMitigationVendor Advisory