{"id":"CVE-2026-102271","summary":"PyJWT: Public keys in DER form are accepted as HMAC secrets, bypassing the CVE-2022-29217 guard","details":"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.","aliases":["GHSA-p4g4-x82p-q773"],"modified":"2026-09-30T03:49:03.005664858Z","published":"2026-09-28T20:31:53.066Z","database_specific":{"cwe_ids":["CWE-347"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/102xxx/CVE-2026-102271.json","cna_assigner":"GitHub_M"},"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-2026-102271.json"},{"type":"ADVISORY","url":"https://github.com/jpadilla/pyjwt/security/advisories/GHSA-p4g4-x82p-q773"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-102271"},{"type":"FIX","url":"https://github.com/jpadilla/pyjwt/commit/2798504fa2663364573cf2d1043d8d7fef389499"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/jpadilla/pyjwt","events":[{"introduced":"83ff831a4d11190e3a0bed781da43f8d84352653"},{"fixed":"2798504fa2663364573cf2d1043d8d7fef389499"},{"fixed":"c6fe464b356ff4b1ebc9ba62172d331a40aa27df"}],"database_specific":{"source":["AFFECTED_FIELD","REFERENCES"],"extracted_events":[{"introduced":"2.4.0"},{"fixed":"2.14.0"}]}}],"versions":["2.13.0","2.12.1","2.12.0","2.11.0","2.10.1","2.10.0","2.9.0","2.8.0","2.7.0","2.6.0","2.5.0","2.4.0"],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-102271.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"}]}