{"id":"CVE-2026-102271","published":"2026-09-28T21:17:15.110","lastModified":"2026-09-28T21:17:15.110","description":"PyJWT is a Python implementation of JSON Web Token standards. From 2.4.0 until 2.14.0, PyJWT HMACAlgorithm.prepare_key is affected because asymmetric-key guard relies on textual markers that are absent from DER encoding. This occurs when an application mixes HMAC and asymmetric algorithms and supplies a DER public key as the shared verification key. As a result, PyJWT uses public DER bytes as an HMAC secret. Consequently, an attacker who knows the public key can forge authenticated HMAC tokens. This issue is fixed in version 2.14.0.","cvssScore":7.4,"cvssSeverity":"HIGH","cvssVector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N","cwes":["CWE-347"],"vendors":[],"products":[],"references":[{"url":"https://github.com/jpadilla/pyjwt/commit/2798504fa2663364573cf2d1043d8d7fef389499","tags":[]},{"url":"https://github.com/jpadilla/pyjwt/releases/tag/2.14.0","tags":[]},{"url":"https://github.com/jpadilla/pyjwt/security/advisories/GHSA-p4g4-x82p-q773","tags":[]}],"exploitRefs":[{"url":"https://github.com/jpadilla/pyjwt/commit/2798504fa2663364573cf2d1043d8d7fef389499","tags":[]},{"url":"https://github.com/jpadilla/pyjwt/releases/tag/2.14.0","tags":[]},{"url":"https://github.com/jpadilla/pyjwt/security/advisories/GHSA-p4g4-x82p-q773","tags":[]}],"hasPoc":true,"ai":null}