Description
fast-jwt provides fast JSON Web Token (JWT) implementation. In 6.1.0 and earlier, the publicKeyPemMatcher regex in fast-jwt/src/crypto.js uses a ^ anchor that is defeated by any leading whitespace in the key string, re-enabling the exact same JWT algorithm confusion attack that CVE-2023-48223 patched.
Affected products
nearform: fast-jwt
References1
- github.com/nearform/fast-jwt/security/advisories/GHSA-mvf2-f6gm… ExploitVendor Advisory
Metrics
- CVSS 3.1
-
9.1
CRITICAL
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N - EPSS — exploit probability
- 0% percentile: 16 · as of 12 November 2026
- CWE
- CWE-327
Could this be exploited in your environment?
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