{"id":"CVE-2026-101918","summary":"PyJWT: Unauthenticated RecursionError DoS in pre-verification payload parse (PyJWKClient.get_signing_key_from_jwt / verify_signature=False)","details":"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.","aliases":["GHSA-42vr-xj54-vc7v"],"modified":"2026-09-30T03:47:04.250639432Z","published":"2026-09-28T20:11:55.278Z","database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-248"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/101xxx/CVE-2026-101918.json"},"references":[{"type":"WEB","url":"https://github.com/jpadilla/pyjwt/releases/tag/2.15.0"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/101xxx/CVE-2026-101918.json"},{"type":"ADVISORY","url":"https://github.com/jpadilla/pyjwt/security/advisories/GHSA-42vr-xj54-vc7v"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-101918"},{"type":"FIX","url":"https://github.com/jpadilla/pyjwt/commit/5fde08a6cf906aa7698de2d6391d88b73006b17b"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/jpadilla/pyjwt","events":[{"introduced":"8041cb607a733a9b5fffe1e9136d55a40bcea25b"},{"fixed":"5fde08a6cf906aa7698de2d6391d88b73006b17b"},{"fixed":"1d41a6478e1562e68ff667fcd703356acf085f68"}],"database_specific":{"extracted_events":[{"introduced":"2.0.0a1"},{"fixed":"2.15.0"}],"source":["AFFECTED_FIELD","REFERENCES"]}}],"versions":["2.14.0","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","2.3.0","2.2.0","2.1.0","2.0.1","2.0.0","2.0.0a2","2.0.0a1"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-101918.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"}]}