---
cve: "CVE-2026-35039"
severity: "CRITICAL"
cvss: 9.1
epss: "0.2%"
vendor: "nearform"
kev: false
exploited: false
published: "2026-04-06 17:17:13"
tags: [cve, security, critical]
source: tsecurity.de CVE-Dossier
exported: "2026-11-09T16:25:48+01:00"
---

# CVE-2026-35039

> 9.1 CRITICAL · 🧪 PoC

## Beschreibung

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.

## CNA-Record (Kanon, cvelistV5)

- CNA: **GitHub_M**
- State: PUBLISHED
- Stand: 2026-05-13 15:12:43
- CNA-CVSS: **9.1** (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N`)

## CISA-Anreicherung (vulnrichment/ADP)

- CISA-SSVC (Coordinator, v2.0.3):
  - Exploitation: **none**
  - Automatable: **yes**
  - Technical Impact: **total**

## CVSS-Vektor

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

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |
| S Scope | Unverändert | good |
| C Vertraulichkeit | Hoch | bad |
| I Integrität | Hoch | bad |
| A Verfügbarkeit | Keine | good |

## Schwachstellen-Klasse

- **CWE-1289** — Improper Validation of Unsafe Equivalence in Input
  The product receives an input value that is used as a resource identifier or other type of reference, but it does not validate or incorrectly validates that the input is equivalent to a potentially-unsafe value.
- **CWE-345** — Insufficient Verification of Data Authenticity
  The product does not sufficiently verify the origin or authenticity of data, in a way that causes it to accept invalid data.
- **CWE-706** — Use of Incorrectly-Resolved Name or Reference
  The product uses a name or reference to access a resource, but the name/reference resolves to a resource that is outside of the intended control sphere.

## Patch verfügbar (OSV)

- 986a77a7d59964ad6eebe9de5681d9134cc435b4 (Commit)
- de121056c6415b58770c60640881eaec67ac4ceb (Commit)

## Referenzen

- <https://github.com/nearform/fast-jwt/security/advisories/GHSA-rp9m-7r4c-75qg>
- <https://github.com/nearform/fast-jwt/commit/de121056c6415b58770c60640881eaec67ac4ceb>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/sicherheitsluecken/cve-2026-35039/) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI WID (CSAF)_