Description
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.
Affected products
nearform: fast-jwt
References3
- github.com/nearform/fast-jwt/security/advisories/GHSA-hm7r-c7qw… ExploitMitigationVendor Advisory
- github.com/nearform/fast-jwt/security/advisories/GHSA-hm7r-c7qw… ExploitMitigationVendor Advisory
- www.rfc-editor.org/rfc/rfc7515.html#section-4.1.11 Technical Description
Metrics
- CVSS 3.1
-
7.5
HIGH
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N - EPSS — exploit probability
- 0% percentile: 5 · as of 12 November 2026
- CWE
- CWE-345CWE-636
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