CVE-2026-35042

fast-jwt provides fast JSON Web Token (JWT) implementation. In 6.1.0 and earlier, fast-jwt does not validate the crit (Critical) Header Parameter defined in RFC 7515 §4.1.11. When a JWS token contains a crit array listing extensions that fast-jwt does not understand, the library accepts the token instead of rejecting it. This violates the MUST requirement in the RFC.

CVSS v3 7.5 HIGH

7.5^/10

CVSS v3 : HIGH

Vector :

Exploitability : 3.9 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact HIGH

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://github.com/nearform/fast-jwt/security/advisories/GHSA-hm7r-c7qw-ghp6	Exploit Mitigation Vendor Advisory
https://www.rfc-editor.org/rfc/rfc7515.html#section-4.1.11	Technical Description
https://github.com/nearform/fast-jwt/security/advisories/GHSA-hm7r-c7qw-ghp6	Exploit Mitigation Vendor Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:nearform:fast-jwt:*:*:*:*:*:node.js:*:*

History

No history.

Information

Published : 2026-04-06 17:17

Updated : 2026-06-17 10:40

NVD link : CVE-2026-35042

Mitre link : CVE-2026-35042

CVE.ORG link : CVE-2026-35042

JSON object : View

Products Affected

nearform

fast-jwt

CWE

CWE-345

Insufficient Verification of Data Authenticity

CWE-636

Not Failing Securely ('Failing Open')

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