{"id":"CVE-2026-102272","state":"PUBLISHED","title":"PyJWT BOM Bypass","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.","publishedAt":"2026-09-28T20:36:31.530Z","updatedAt":"2026-09-29T14:45:44.138Z","severity":{"score":7.4,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["jpadilla pyjwt"],"affected":[{"vendor":"jpadilla","product":"pyjwt","versions":[{"version":">= 2.13.0, < 2.14.0","status":"affected"}]}],"references":["https://github.com/jpadilla/pyjwt/security/advisories/GHSA-r6x4-923q-g947","https://github.com/jpadilla/pyjwt/commit/180783930de91876bc0d601f826a1f2956057291","https://github.com/jpadilla/pyjwt/releases/tag/2.14.0"],"weaknesses":["CWE-347"],"ingestedAt":"2026-10-29T20:10:13.529Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/102xxx/CVE-2026-102272.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-102272","state":"PUBLISHED","datePublished":"2026-09-28T20:36:31.530Z","dateUpdated":"2026-09-29T14:45:44.138Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-09-28T20:11:16.658Z"},"containers":{"cna":{"title":"PyJWT BOM Bypass","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"jpadilla","product":"pyjwt","versions":[{"version":">= 2.13.0, < 2.14.0","status":"affected"}]}],"references":[{"url":"https://github.com/jpadilla/pyjwt/security/advisories/GHSA-r6x4-923q-g947","name":"https://github.com/jpadilla/pyjwt/security/advisories/GHSA-r6x4-923q-g947","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/jpadilla/pyjwt/commit/180783930de91876bc0d601f826a1f2956057291","name":"https://github.com/jpadilla/pyjwt/commit/180783930de91876bc0d601f826a1f2956057291","tags":["x_refsource_MISC"]},{"url":"https://github.com/jpadilla/pyjwt/releases/tag/2.14.0","name":"https://github.com/jpadilla/pyjwt/releases/tag/2.14.0","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":7.4,"baseSeverity":"HIGH","confidentialityImpact":"HIGH","integrityImpact":"HIGH","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-347","lang":"en","description":"CWE-347: Improper Verification of Cryptographic Signature","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-09-28T20:36:31.530Z"},"source":{"advisory":"GHSA-r6x4-923q-g947","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/jpadilla/pyjwt/security/advisories/GHSA-r6x4-923q-g947","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-09-29T14:45:38.333972Z","id":"CVE-2026-102272","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-09-29T14:45:44.138Z"}}]}}}