CVE-2026-107724 fast-jwt - Authentication Bypass

fast-jwt 6.2.4 contains a broken authentication caused by misclassification of raw serialized public JWK or JWKS JSON as HMAC secret in src/crypto.js, letting attackers create tokens with arbitrary claims, exploit requires knowledge of exact serialized public-key bytes.

CVSS base score 7.4 /10
High
CISA KEV
Not listed
Public exploit
None known
EPSS
0.22% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Authentication Bypass
Impact
Broken Authentication
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Published
8 October 2026
Updated
15 October 2026
Weakness
CWE-347

Vendor fix

Update to version 6.3.0 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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