fast-jwt provides fast JSON Web Token (JWT) implementation. Prior to 6.3.1, fast-jwt createVerifier accepts an unsigned JWT when key is an empty string or null and algorithms is a non-empty allowlist. Falsy synchronous keys bypass prepareKe…
Exact source revision recorded 7 Nov 2026 05:38:23 UTC. It does not establish the source's current position. Latest evidence.
euvd · EUVD-2026-95344
Publishedfast-jwt provides fast JSON Web Token (JWT) implementation. Prior to 6.3.1, fast-jwt createVerifier accepts an unsigned JWT when key is an empty string or null and algorithms is a non-empty allowlist. Falsy synchronous keys bypass prepareKeyOrSecret, allowedAlgorithms remains active, hasKey is false, and the empty signature avoids the verifySignature gate. An attacker can therefore submit a token containing arbitrary claims without possessing a signing key, resulting in authentication or authorization bypass. Claim validators still run, and non-empty keys, an empty key without algorithms, and the async key resolver path do not have this behavior. This issue is fixed in version 6.3.1.
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Original publisher date fields
datePublished: Oct 8, 2026, 9:44:06 PM
dateUpdated: Oct 9, 2026, 2:32:14 PM
- Source published
- Oct 8, 2026, 9:44:06 PM (timezone not stated)
- Source modified
- Oct 9, 2026, 2:32:14 PM (timezone not stated)
- Observed here
- 7 Nov 2026 05:38:23 UTC
- Source terms
- ENISA EUVD · source terms and attribution apply
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EUVD CVSS 3.1 · 7.4 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N