---
cve: "CVE-2026-6673"
severity: "MEDIUM"
cvss: 6.4
epss: "30%"
vendor: "Mattermost"
kev: false
exploited: false
published: "2026-06-22 14:17:51"
tags: [cve, security, medium]
source: tsecurity.de CVE-Dossier
exported: "2026-09-08T19:45:46+02:00"
---

# CVE-2026-6673

> 6.4 MEDIUM

## Beschreibung

Mattermost versions 11.7.x <= 11.7.0, 11.6.x <= 11.6.2, 11.5.x <= 11.5.5, 10.11.x <= 10.11.17 fail to authenticate Atlassian Connect installed callbacks, allowing a remote unauthenticated attacker to inject a rogue sharedSecret and disrupt the Jira integration via POST to /ac/installed during the pending-install window.. Mattermost Advisory ID: MMSA-2026-00654

## CVSS-Vektor

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

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

## Patch verfügbar (OSV)

- 79ba3d3d83ef1562d08ffd2d29d3d9cc2636a41c (Commit)
- 16c42cd8677fcc91383da3b0cc85b8c9c0c231c3 (Commit)

## Referenzen

- <https://mattermost.com/security-updates>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-6673) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_