critical9.1
CVE-2026-35039
fast-jwt: Cache Confusion via cacheKeyBuilder Collisions Can Return Claims From a Different Token (Identity/Authorization Mixup)
Impact
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.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| npm | fast-jwt | >= 0.0.1, < 6.2.0 | 6.2.0 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Nearform | Fast-Jwt | from 0.1.0 before 6.1.0 |