{"api_version":"1","generated_at":"2026-05-14T02:28:30+00:00","cve":"CVE-2026-44351","urls":{"html":"https://cve.report/CVE-2026-44351","api":"https://cve.report/api/cve/CVE-2026-44351.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-44351","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-44351"},"summary":{"title":"fast-jwt: Empty HMAC secret accepted via async key resolver - JWT auth bypass","description":"fast-jwt provides fast JSON Web Token (JWT) implementation. Prior to 6.2.4, a critical authentication-bypass vulnerability in fast-jwt's async key-resolver flow allows any unauthenticated attacker to forge arbitrary JWTs that are accepted as authentic. When the application's key resolver returns an empty string (''), for example via the common keys[decoded.header.kid] || '' JWKS-style fallback, fast-jwt converts it to a zero-length Buffer, hands it to crypto.createSecretKey, derives allowedAlgorithms = ['HS256','HS384','HS512'] from it, and then verifies the token's signature against an empty-key HMAC. The attacker simply computes HMAC-SHA256(key='', input='${header}.${payload}'), which Node accepts without complaint — and the verifier returns the attacker-chosen payload (sub, admin, scopes, etc.) as authentic. This vulnerability is fixed in 6.2.4.","state":"PUBLISHED","assigner":"GitHub_M","published_at":"2026-05-13 20:16:22","updated_at":"2026-05-13 20:16:22"},"problem_types":["CWE-287","CWE-326","CWE-1391","CWE-287 CWE-287: Improper Authentication","CWE-326 CWE-326: Inadequate Encryption Strength","CWE-1391 CWE-1391: Use of Weak Credentials"],"metrics":[{"version":"3.1","source":"security-advisories@github.com","type":"Secondary","score":"9.1","severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","baseScore":9.1,"baseSeverity":"CRITICAL","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"NONE"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"9.1","severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","data":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":9.1,"baseSeverity":"CRITICAL","confidentialityImpact":"HIGH","integrityImpact":"HIGH","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","version":"3.1"}}],"references":[{"url":"https://github.com/nearform/fast-jwt/security/advisories/GHSA-gmvf-9v4p-v8jc","name":"https://github.com/nearform/fast-jwt/security/advisories/GHSA-gmvf-9v4p-v8jc","refsource":"security-advisories@github.com","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-44351","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-44351","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"nearform","product":"fast-jwt","version":"affected < 6.2.4","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"product":"fast-jwt","vendor":"nearform","versions":[{"status":"affected","version":"< 6.2.4"}]}],"descriptions":[{"lang":"en","value":"fast-jwt provides fast JSON Web Token (JWT) implementation. Prior to 6.2.4, a critical authentication-bypass vulnerability in fast-jwt's async key-resolver flow allows any unauthenticated attacker to forge arbitrary JWTs that are accepted as authentic. When the application's key resolver returns an empty string (''), for example via the common keys[decoded.header.kid] || '' JWKS-style fallback, fast-jwt converts it to a zero-length Buffer, hands it to crypto.createSecretKey, derives allowedAlgorithms = ['HS256','HS384','HS512'] from it, and then verifies the token's signature against an empty-key HMAC. The attacker simply computes HMAC-SHA256(key='', input='${header}.${payload}'), which Node accepts without complaint — and the verifier returns the attacker-chosen payload (sub, admin, scopes, etc.) as authentic. This vulnerability is fixed in 6.2.4."}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":9.1,"baseSeverity":"CRITICAL","confidentialityImpact":"HIGH","integrityImpact":"HIGH","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-287","description":"CWE-287: Improper Authentication","lang":"en","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-326","description":"CWE-326: Inadequate Encryption Strength","lang":"en","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-1391","description":"CWE-1391: Use of Weak Credentials","lang":"en","type":"CWE"}]}],"providerMetadata":{"dateUpdated":"2026-05-13T19:12:33.347Z","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","shortName":"GitHub_M"},"references":[{"name":"https://github.com/nearform/fast-jwt/security/advisories/GHSA-gmvf-9v4p-v8jc","tags":["x_refsource_CONFIRM"],"url":"https://github.com/nearform/fast-jwt/security/advisories/GHSA-gmvf-9v4p-v8jc"}],"source":{"advisory":"GHSA-gmvf-9v4p-v8jc","discovery":"UNKNOWN"},"title":"fast-jwt: Empty HMAC secret accepted via async key resolver - JWT auth bypass"}},"cveMetadata":{"assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","assignerShortName":"GitHub_M","cveId":"CVE-2026-44351","datePublished":"2026-05-13T19:12:33.347Z","dateReserved":"2026-05-05T19:52:59.148Z","dateUpdated":"2026-05-13T19:12:33.347Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-05-13 20:16:22","lastModifiedDate":"2026-05-13 20:16:22","problem_types":["CWE-287","CWE-326","CWE-1391","CWE-287 CWE-287: Improper Authentication","CWE-326 CWE-326: Inadequate Encryption Strength","CWE-1391 CWE-1391: Use of Weak Credentials"],"metrics":{"cvssMetricV31":[{"source":"security-advisories@github.com","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","baseScore":9.1,"baseSeverity":"CRITICAL","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"NONE"},"exploitabilityScore":3.9,"impactScore":5.2}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"44351","Ordinal":"1","Title":"fast-jwt: Empty HMAC secret accepted via async key resolver - JW","CVE":"CVE-2026-44351","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"44351","Ordinal":"1","NoteData":"fast-jwt provides fast JSON Web Token (JWT) implementation. Prior to 6.2.4, a critical authentication-bypass vulnerability in fast-jwt's async key-resolver flow allows any unauthenticated attacker to forge arbitrary JWTs that are accepted as authentic. When the application's key resolver returns an empty string (''), for example via the common keys[decoded.header.kid] || '' JWKS-style fallback, fast-jwt converts it to a zero-length Buffer, hands it to crypto.createSecretKey, derives allowedAlgorithms = ['HS256','HS384','HS512'] from it, and then verifies the token's signature against an empty-key HMAC. The attacker simply computes HMAC-SHA256(key='', input='${header}.${payload}'), which Node accepts without complaint — and the verifier returns the attacker-chosen payload (sub, admin, scopes, etc.) as authentic. This vulnerability is fixed in 6.2.4.","Type":"Description","Title":"fast-jwt: Empty HMAC secret accepted via async key resolver - JW"}]}}}