CVE-2026-35039: nearform fast-jwt · Insufficient Verification of Data Authenticity
Affects nearform fast-jwtSource CVE Database V5
Not known to be exploited · CVSS 9.1 Critical : upgrade to 6.2.0 as a priority.
Data as of 30 Oct 2026, 06:59 UTC
Contested
Critical score, yet low EPSS after six months- EPSS
- 0.2% chance of exploitation in 30 days – higher than 11% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 6.2.0
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:NExploitation evidence
Disclosed: evidence found.
CVE published 6 Apr 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
What to do
Upgrade nearform fast-jwt to 6.2.0.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| nearformfast-jwt | Affected
| Fixed in
|
npmfast-jwtpkg:npm/fast-jwtOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Upgrade fast-jwt to version 6.2.0 or later, which contains the official patch fixing the cache key uniqueness issue. Until upgrading, avoid using custom cacheKeyBuilder implementations that do not guarantee unique keys per token to prevent cache collisions.
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.