CVE-2026-35039 — Insufficient Verification of Data Authenticity in Fast-jwt

CWE-345 — Insufficient Verification of Data AuthenticityCWE-706 — Use of Incorrectly-Resolved Name or ReferenceCWE-1289 — Improper Validation of Unsafe Equivalence in Input4 documents4 sources
Severity
9.1CRITICALNVD
EPSS
0.0%
top 90.85%
CISA KEV
Not in KEV
Exploit
No known exploits
Affected products
1
Nearform Fast-jwt
Timeline
Latest updateApr 3
PublishedApr 6

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.

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:NExploitability: 3.9 | Impact: 5.2

Affected Packages2 packages

▶npmnearform/fast-jwt0.0.1 — 6.2.0
▶CVEListV5nearform/fast-jwt>= 0.0.1, < 6.2.0

🔴Vulnerability Details

2
OSV
fast-jwt: Cache Confusion via cacheKeyBuilder Collisions Can Return Claims From a Different Token (Identity/Authorization Mixup)↗2026-04-03
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GHSA
fast-jwt: Cache Confusion via cacheKeyBuilder Collisions Can Return Claims From a Different Token (Identity/Authorization Mixup)↗2026-04-03
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🕵️Threat Intelligence

1
Wiz
CVE-2026-35039 Impact, Exploitability, and Mitigation Steps | Wiz↗
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