---
cve: "CVE-2026-85394"
severity: "CRITICAL"
cvss: 9.1
epss: "56.8%"
vendor: "Generic Security"
kev: false
exploited: false
published: "2026-09-03 19:17:31"
tags: [cve, security, critical]
source: tsecurity.de CVE-Dossier
exported: "2026-09-06T16:17:28+02:00"
---

# CVE-2026-85394

> 9.1 CRITICAL

## Beschreibung

python-jose through 3.5.0 fails to properly validate asymmetric keys in HMAC initialization, accepting DER-encoded public keys that lack PEM armor or SSH prefixes. Attackers holding the service's public key can forge HS256 tokens that pass verification when algorithms are not explicitly restricted. This is an incomplete fix for CVE-2024-33663.

## 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 |

## Patch verfügbar (OSV)

- 018b310ddb8b50dcfd09a0c152117835a21dd656 (Commit)

## Referenzen

- <https://github.com/advisories/GHSA-6c5p-j8vq-pqhj>
- <https://github.com/mpdavis/python-jose>
- <https://github.com/mpdavis/python-jose/blob/018b310ddb8b50dcfd09a0c152117835a21dd656/jose/backends/native.py>
- <https://github.com/mpdavis/python-jose/blob/018b310ddb8b50dcfd09a0c152117835a21dd656/jose/utils.py>
- <https://github.com/mpdavis/python-jose/issues/414>
- <https://www.vulncheck.com/advisories/python-jose-through-3.5.0-algorithm-confusion-via-der-encoded-public-key-as-hmac-secret>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-85394) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_