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CVE-2026-35042

7.5 · HIGH

fast-jwt provides fast JSON Web Token (JWT) implementation.

Published Apr 6, 2026CWE-345EPSS 0.20%

Overview

CVE-2026-35042 is a high-severity vulnerability. It was published on April 6, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/nearform/fast-jwt/security/advisories/GHSA-hm7r-c7qw-ghp6Refwww.rfc-editor.org/rfc/rfc7515.html#section-4.1.11GitHubgithub.com/nearform/fast-jwt/security/advisories/GHSA-hm7r-c7qw-ghp6

How CyberStrike helps

Frequently asked questions

What is CVE-2026-35042?

CVE-2026-35042 is a high-severity vulnerability. It was published on April 6, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).

How severe is CVE-2026-35042?

This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-35042?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-35042?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-35042 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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