CVE-2026-107722 fast-jwt - Authentication Bypass

fast-jwt 6.2.0 to 6.3.0 contains an authentication bypass caused by misclassification of RSA public-key text as HMAC secret due to improper PEM header detection, letting attackers sign arbitrary HS256 claims, exploit requires attacker knowledge of public key bytes.

CVSS base score 9.8 /10
Critical
CISA KEV
Not listed
Public exploit
None known
EPSS
0.27% 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:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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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