{"id":"CVE-2026-101918","state":"PUBLISHED","title":"PyJWT: Unauthenticated RecursionError DoS in pre-verification payload parse (PyJWKClient.get_signing_key_from_jwt / verify_signature=False)","description":"PyJWT is a Python implementation of JSON Web Token standards. From 2.0.0a1 until 2.15.0, PyJWT PyJWKClient.get_signing_key_from_jwt is affected because payload parser catches ValueError but not RecursionError. This occurs when an attacker-controlled recursively nested payload reaches json.loads. As a result, documented PyJWT exception handling does not contain the failure. Consequently, an unauthenticated request can raise an exception that may produce an HTTP 500 response. The advisory-defined affected implementation also includes jwt/api_jwt.py, verify_signature=False. This issue is fixed in version 2.15.0.","publishedAt":"2026-09-28T20:11:55.278Z","updatedAt":"2026-09-29T13:57:29.516Z","severity":{"score":5.3,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","source":"GitHub_M"},"assigner":"GitHub_M","products":["jpadilla pyjwt"],"affected":[{"vendor":"jpadilla","product":"pyjwt","versions":[{"version":">= 2.0.0a1, < 2.15.0","status":"affected"}]}],"references":["https://github.com/jpadilla/pyjwt/security/advisories/GHSA-42vr-xj54-vc7v","https://github.com/jpadilla/pyjwt/commit/5fde08a6cf906aa7698de2d6391d88b73006b17b","https://github.com/jpadilla/pyjwt/releases/tag/2.15.0"],"weaknesses":["CWE-248"],"ingestedAt":"2026-10-29T20:10:13.529Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/101xxx/CVE-2026-101918.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-101918","state":"PUBLISHED","datePublished":"2026-09-28T20:11:55.278Z","dateUpdated":"2026-09-29T13:57:29.516Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-09-28T15:55:37.908Z"},"containers":{"cna":{"title":"PyJWT: Unauthenticated RecursionError DoS in pre-verification payload parse (PyJWKClient.get_signing_key_from_jwt / verify_signature=False)","descriptions":[{"lang":"en","value":"PyJWT is a Python implementation of JSON Web Token standards. From 2.0.0a1 until 2.15.0, PyJWT PyJWKClient.get_signing_key_from_jwt is affected because payload parser catches ValueError but not RecursionError. This occurs when an attacker-controlled recursively nested payload reaches json.loads. As a result, documented PyJWT exception handling does not contain the failure. Consequently, an unauthenticated request can raise an exception that may produce an HTTP 500 response. The advisory-defined affected implementation also includes jwt/api_jwt.py, verify_signature=False. This issue is fixed in version 2.15.0."}],"affected":[{"vendor":"jpadilla","product":"pyjwt","versions":[{"version":">= 2.0.0a1, < 2.15.0","status":"affected"}]}],"references":[{"url":"https://github.com/jpadilla/pyjwt/security/advisories/GHSA-42vr-xj54-vc7v","name":"https://github.com/jpadilla/pyjwt/security/advisories/GHSA-42vr-xj54-vc7v","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/jpadilla/pyjwt/commit/5fde08a6cf906aa7698de2d6391d88b73006b17b","name":"https://github.com/jpadilla/pyjwt/commit/5fde08a6cf906aa7698de2d6391d88b73006b17b","tags":["x_refsource_MISC"]},{"url":"https://github.com/jpadilla/pyjwt/releases/tag/2.15.0","name":"https://github.com/jpadilla/pyjwt/releases/tag/2.15.0","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"LOW","baseScore":5.3,"baseSeverity":"MEDIUM","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-248","lang":"en","description":"CWE-248: Uncaught Exception","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-09-28T20:11:55.278Z"},"source":{"advisory":"GHSA-42vr-xj54-vc7v","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-09-29T13:55:59.459735Z","id":"CVE-2026-101918","options":[{"Exploitation":"poc"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-09-29T13:57:29.516Z"}}]}}}