{"id":"CVE-2026-35042","summary":"fast-jwt accepts unknown `crit` header extensions (RFC 7515 §4.1.11 MUST violation)","details":"fast-jwt provides fast JSON Web Token (JWT) implementation. In 6.1.0 and earlier, fast-jwt does not validate the crit (Critical) Header Parameter defined in RFC 7515 §4.1.11. When a JWS token contains a crit array listing extensions that fast-jwt does not understand, the library accepts the token instead of rejecting it. This violates the MUST requirement in the RFC.","aliases":["GHSA-hm7r-c7qw-ghp6"],"modified":"2026-07-08T08:12:59.066035899Z","published":"2026-04-06T17:02:12.180Z","database_specific":{"cwe_ids":["CWE-345","CWE-636"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/35xxx/CVE-2026-35042.json","cna_assigner":"GitHub_M"},"references":[{"type":"WEB","url":"https://www.rfc-editor.org/rfc/rfc7515.html#section-4.1.11"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/35xxx/CVE-2026-35042.json"},{"type":"ADVISORY","url":"https://github.com/nearform/fast-jwt/security/advisories/GHSA-hm7r-c7qw-ghp6"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-35042"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/nearform/fast-jwt","events":[{"introduced":"0"},{"fixed":"e07b1fd23f02a47f1be677a21a4f07607b478e66"}],"database_specific":{"cpe":"cpe:2.3:a:nearform:fast-jwt:*:*:*:*:*:node.js:*:*","extracted_events":[{"introduced":"0"},{"last_affected":"6.1.0"},{"fixed":"6.2.0"}],"source":["AFFECTED_FIELD","CPE_RANGE"]}}],"versions":["v6.1.0","v2.0.0","v1.7.2","v1.7.1","v1.7.0","v1.6.1","v1.6.0","v1.5.4","v1.5.3","v1.5.2","v1.5.1","v1.5.0","v1.4.1","v1.4.0","v1.3.2","v1.3.0","v1.2.0","v1.1.3","v1.1.2","v1.1.1","v1.1.0","v1.0.0","v0.5.1","v0.5.0","v0.4.2","v0.4.1","v0.4.0","v0.3.1","v0.3.0","v0.2.0","v0.1.1","v0.1.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-35042.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N"}]}