---
cve: "CVE-2026-109284"
severity: "MEDIUM"
cvss: 5.3
epss: ""
vendor: "open-webui"
kev: false
exploited: false
published: "2026-10-12 17:17:21"
tags: [cve, security, medium]
source: tsecurity.de CVE-Dossier
exported: "2026-10-23T15:13:12+02:00"
---

# CVE-2026-109284

> 5.3 MEDIUM · 🧪 PoC

## Beschreibung

Open WebUI from 0.11.0 before 0.11.4 contains an improper authorization vulnerability in the chat fork handler, which places forked chats in the source chat's folder without checking folder write access. Shared folder members downgraded to read-only can call POST /api/v1/chats/{id}/fork on chats they created there while they had write access, inserting attacker-controlled chats visible to the folder owner and members.

## CNA-Record (Kanon, cvelistV5)

- CNA: **VulnCheck**
- State: PUBLISHED
- Stand: 2026-10-13 16:55:38
- CNA-CVSS: **5.3** (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N`)

## CISA-Anreicherung (vulnrichment/ADP)

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

## CVSS-Vektor

```
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Gering | warn |
| UI Interaktion | Keine | bad |

## Schwachstellen-Klasse

- **CWE-862** — Missing Authorization
  The product does not perform an authorization check when an actor attempts to access a resource or perform an action.

## Angriffsmuster (CAPEC)

- [CAPEC-665 — Exploitation of Thunderbolt Protection Flaws](https://capec.mitre.org/data/definitions/665.html) _(Severity: Very High)_

## ATT&CK-Techniken

- [T1211 — Exploitation for Defensive Evasion](https://attack.mitre.org/techniques/T1211/)
- [T1542.002 — Pre-OS Boot: Component Firmware](https://attack.mitre.org/techniques/T1542/002/)
- [T1556 — Modify Authentication Process](https://attack.mitre.org/techniques/T1556/)

## Patch verfügbar (OSV)

- 8bd8b4fac5e059578ac0c74b3c18d11139f88b7d (Commit)

## Referenzen

- <https://github.com/open-webui/open-webui/security/advisories/GHSA-6fjc-5cg3-mgvh>
- <https://www.vulncheck.com/advisories/open-webui-0.11.0-before-0.11.4-improper-authorization-via-chat-fork-endpoint>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/sicherheitsluecken/cve-2026-109284/) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI WID (CSAF)_