CVE-2026-35039

Name: CVE-2026-35039
Creator: NVD / NIST
Published: 2026-04-06T17:17:13.243+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.1/10EPSS 0.21%

Last modified Jun 17, 2026

CVE-2026-35039 is a critical-severity vulnerability rated 9.1/10 on the CVSS scale. fast-jwt provides fast JSON Web Token (JWT) implementation. From 0.0.1 to before 6.2.0, setting up a custom cacheKeyBuilder method which does not properly create unique keys for different tokens can lead to cache collisions. EPSS estimates a 0.21% chance of exploitation in the next 30 days.

Description

fast-jwt provides fast JSON Web Token (JWT) implementation. From 0.0.1 to before 6.2.0, setting up a custom cacheKeyBuilder method which does not properly create unique keys for different tokens can lead to cache collisions. This could cause tokens to be mis-identified during the verification process leading to valid tokens returning claims from different valid tokens and users being mis-identified as other users based on the wrong token. Version 6.2.0 contains a patch.

Metrics

CVSS 3.1

9.1/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

EPSS Probability

0.21%

11.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Nearform	Fast-Jwt	>= 0.1.0, < 6.1.0

References

https://github.com/nearform/fast-jwt/commit/de121056c6415b58770c60640881eaec67ac4cebPatch
https://github.com/nearform/fast-jwt/security/advisories/GHSA-rp9m-7r4c-75qgMitigation, Vendor Advisory

Timeline

Published: Apr 6, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-35039?

How severe is CVE-2026-35039?

CVE-2026-35039 has a CVSS score of 9.1/10 (CRITICAL severity). The EPSS model estimates a 0.21% probability of exploitation in the next 30 days.

How do I fix CVE-2026-35039?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-35039?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST