Vulnerability in Nearform Fast-Jwt
CVE-2026-35039
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.
EPSS exploit prediction
EPSS: 0.002 (11.5th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 12th percentile — 11.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: +0.000
Affected products
- Nearform Fast-Jwt — versions >= 0.0.1, < 6.2.0
Weakness classification (CWE)
References
- github.com/nearform/fast-jwt/security/advisories/GHSA-rp9m-7r4c-75qg (Mitigation, Vendor Advisory)
- github.com/nearform/fast-jwt/commit/de121056c6415b58770c60640881eaec67ac4ceb (Patch)
Frequently asked questions
- What is CVE-2026-35039?
- CVE-2026-35039 is a critical-severity vulnerability in Nearform Fast-Jwt, classified under Insufficient Verification of Data Authenticity. CVSS score: 9.1/10. Published 2026-04-06.
- How severe is CVE-2026-35039?
- Critical severity. CVSS v3 base score is 9.1 out of 10.