{"id":"CVE-2026-102272","summary":"PyJWT BOM Bypass","details":"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.","aliases":["GHSA-r6x4-923q-g947"],"modified":"2026-09-30T03:49:03.371443736Z","published":"2026-09-28T20:36:31.530Z","database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-347"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/102xxx/CVE-2026-102272.json"},"references":[{"type":"WEB","url":"https://github.com/jpadilla/pyjwt/releases/tag/2.14.0"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/102xxx/CVE-2026-102272.json"},{"type":"ADVISORY","url":"https://github.com/jpadilla/pyjwt/security/advisories/GHSA-r6x4-923q-g947"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-102272"},{"type":"FIX","url":"https://github.com/jpadilla/pyjwt/commit/180783930de91876bc0d601f826a1f2956057291"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/jpadilla/pyjwt","events":[{"introduced":"7144e4534c34810f4525dc4578a32addd8212cff"},{"fixed":"180783930de91876bc0d601f826a1f2956057291"},{"fixed":"c6fe464b356ff4b1ebc9ba62172d331a40aa27df"}],"database_specific":{"extracted_events":[{"introduced":"2.13.0"},{"fixed":"2.14.0"}],"source":["AFFECTED_FIELD","REFERENCES"]}}],"versions":["2.13.0"],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-102272.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N"}]}