---
cve: "CVE-2026-4858"
severity: "HIGH"
cvss: 8.0
epss: "0.3%"
vendor: "Mattermost"
kev: false
exploited: false
published: "2026-05-21 09:16:30"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-10-31T02:49:55+01:00"
---

# CVE-2026-4858

> 8.0 HIGH

## Beschreibung

Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to check integration URL for path traversal which allows an malicious authenticated user  to call an arbitrary API via system admin Mattermost auth token using via path traversal in integration action URL.. Mattermost Advisory ID: MMSA-2026-00640

## CNA-Record (Kanon, cvelistV5)

- CNA: **Mattermost**
- State: PUBLISHED
- Stand: 2026-05-22 03:55:26
- CNA-CVSS: **8.0** (`CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:H`)

## CISA-Anreicherung (vulnrichment/ADP)

- CISA-SSVC (Coordinator, v2.0.3):
  - Exploitation: **none**
  - Automatable: **no**
  - Technical Impact: **total**

## CVSS-Vektor

```
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/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 | Verändert | bad |
| C Vertraulichkeit | Hoch | bad |
| I Integrität | Hoch | bad |
| A Verfügbarkeit | Hoch | bad |

## Schwachstellen-Klasse

- **CWE-22** — Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
  The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.

## Angriffsmuster (CAPEC)

- [CAPEC-64 — Using Slashes and URL Encoding Combined to Bypass Validation Logic](https://capec.mitre.org/data/definitions/64.html) _(Severity: High)_
- [CAPEC-76 — Manipulating Web Input to File System Calls](https://capec.mitre.org/data/definitions/76.html) _(Severity: Very High)_
- [CAPEC-78 — Using Escaped Slashes in Alternate Encoding](https://capec.mitre.org/data/definitions/78.html) _(Severity: High)_
- [CAPEC-79 — Using Slashes in Alternate Encoding](https://capec.mitre.org/data/definitions/79.html) _(Severity: High)_
- [CAPEC-126 — Path Traversal](https://capec.mitre.org/data/definitions/126.html) _(Severity: Very High)_

## Patch verfügbar (OSV)

- f6760151c4a7b4b9d0807fa18892aaf24a3e190e (Commit)
- 292d4b7ea15b49a29989129758f25be37aec946e (Commit)

## BSI-Hinweise (deutsch)

- [Mattermost: Mehrere Schwachstellen ermöglichen nicht spezifizierten Angriff](https://wid.cert-bund.de/portal/wid/sicherheitshinweis/WID-SEC-W-2026-1173) — _BSI-Einstufung: mittel_
  Ein Angreifer kann mehrere Schwachstellen in Mattermost ausnutzen, um einen nicht näher spezifizierten Angriff durchzuführen.

## Referenzen

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

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/sicherheitsluecken/cve-2026-4858/) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI WID (CSAF)_