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HIGHCVE-2026-35042Published Modified CNA GitHub_M

CVE-2026-35042: fast-jwt accepts unknown `crit` header extensions (RFC 7515 §4.1.11 MUST violation)

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.

Metrics

CVSS v3.1
7.5
Severity
HIGH
Fixed in
—
Affected Products
1
Affected packages
  • nearform / fast-jwt
    <= 6.1.0
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
References