{"id":"CVE-2026-102271","state":"PUBLISHED","title":"PyJWT: Public keys in DER form are accepted as HMAC secrets, bypassing the CVE-2022-29217 guard","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.","publishedAt":"2026-09-28T20:31:53.066Z","updatedAt":"2026-10-01T14:57:42.294Z","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":">= 2.4.0, < 2.14.0","status":"affected"}]}],"references":["https://github.com/jpadilla/pyjwt/security/advisories/GHSA-p4g4-x82p-q773","https://github.com/jpadilla/pyjwt/commit/2798504fa2663364573cf2d1043d8d7fef389499","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-2026-102271.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-102271","state":"PUBLISHED","datePublished":"2026-09-28T20:31:53.066Z","dateUpdated":"2026-10-01T14:57:42.294Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-09-28T20:11:16.658Z"},"containers":{"cna":{"title":"PyJWT: Public keys in DER form are accepted as HMAC secrets, bypassing the CVE-2022-29217 guard","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"jpadilla","product":"pyjwt","versions":[{"version":">= 2.4.0, < 2.14.0","status":"affected"}]}],"references":[{"url":"https://github.com/jpadilla/pyjwt/security/advisories/GHSA-p4g4-x82p-q773","name":"https://github.com/jpadilla/pyjwt/security/advisories/GHSA-p4g4-x82p-q773","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/jpadilla/pyjwt/commit/2798504fa2663364573cf2d1043d8d7fef389499","name":"https://github.com/jpadilla/pyjwt/commit/2798504fa2663364573cf2d1043d8d7fef389499","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":"2026-09-28T20:31:53.066Z"},"source":{"advisory":"GHSA-p4g4-x82p-q773","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/jpadilla/pyjwt/security/advisories/GHSA-p4g4-x82p-q773","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-10-01T14:57:03.181101Z","id":"CVE-2026-102271","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":"2026-10-01T14:57:42.294Z"}}]}}}