Auth bypass in Open-Webui
CVE-2026-109284
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.
Vulnerability class: Broken Access Control
Published .
CVSS v3 metric
CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- github.com/open-webui/open-webui/security/advisories/GHSA-6fjc-5cg3-mgvh (vendor-advisory)
- www.vulncheck.com/advisories/open-webui-0.11.0-before-0.11.4-improper-authoriza… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-109284?
- CVE-2026-109284 is a medium-severity vulnerability in Open-Webui, classified under Missing Authorization. CVSS score: 4.3/10. Published 2026-10-12.
- How severe is CVE-2026-109284?
- Medium severity. CVSS v3 base score is 4.3 out of 10.