# CVE-2026-35042

## Summary

- **CVE ID:** CVE-2026-35042
- **Severity:** HIGH
- **CVSS Score:** 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N)
- **CWE:** CWE-345, CWE-636
- **Published:** Apr 6, 2026
- **Last Modified:** Apr 7, 2026

## 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.

## Affected Products

- nearform — fast-jwt (<= 6.1.0)

## References

- [CNA](https://github.com/nearform/fast-jwt/security/advisories/GHSA-hm7r-c7qw-ghp6)
- [CNA](https://www.rfc-editor.org/rfc/rfc7515.html#section-4.1.11)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.15%
- **EPSS Percentile:** 5.0

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._