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.
References (1)
Core 1
Core References
X_Refsource_Confirm x_refsource_confirm
https://github.com/nearform/fast-jwt/security/advisories/GHSA-mvf2-f6gm-w987
Scores
CVSS v3
9.1
EPSS
0.0024
EPSS Percentile
14.2%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CISA SSVC
Vulnrichment
Exploitation
poc
Automatable
yes
Technical Impact
total
Details
CWE
CWE-327
Status
published
Products (3)
nearform/fast-jwt
< 6.2.0
nearform/fast-jwt
<= 6.1.0
npm/fast-jwt
0npm
Published
Apr 06, 2026
Tracked Since
Apr 06, 2026