CVE-2026-34950
CRITICALfast-jwt has an incomplete fix for CVE-2023-48223: JWT Algorithm Confusion via Whitespace-Prefixed RSA Public Key
Title source: cnaDescription
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.
Scores
CVSS v3
9.1
EPSS
0.0002
EPSS Percentile
4.3%
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