CVE-2026-107720fast-jwt: createVerifier accepts unsigned JWTs when key is '' or null and algorithms is explicitly set
Updated under an hour ago ()
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It affects nearform fast-jwt. Add what you run to find out whether that includes you.
EPSS puts the chance of exploitation in the next 30 days at 0.26%, higher than 16% of scored CVEs.
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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 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.
- CVSS
- 7.4 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
- Weakness (CWE)
- CWE-20, CWE-347
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- 0.26% (percentile 16)
- Assigned by
- GitHub_M
- NVD analysis
- Deferred
- Record last updated
- Oct 9, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
nearform fast-jwt nearform:fast_jwt (from the name) | before 6.3.1 | CNA record |
References
- https://github.com/nearform/fast-jwt/security/advisories/GHSA-8wpc-h4q6-8fxvx-refsource-confirm
- https://github.com/nearform/fast-jwt/pull/649x-refsource-misc
- https://github.com/nearform/fast-jwt/commit/e22a151e83bf6d5e54e281216982d204d5665534x-refsource-misc
- https://github.com/nearform/fast-jwt/releases/tag/v6.3.1x-refsource-misc
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.