CVE-2026-109284: Open WebUI 0.11.0 before 0.11.4 Improper Authorization via Chat Fork Endpoint
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.
Affected Software
Event History
Frequently Asked Questions
Which users can exploit this issue?
A shared-folder member who has been downgraded to read-only may still exploit it, but only for chats they created in that folder while they previously had write access.
What access does an attacker need?
The attacker needs low-privileged authenticated access and must be able to call the chat fork endpoint for an eligible chat. No user interaction is required.
What is the impact of successful exploitation?
An attacker can insert attacker-controlled forked chats into the source chat's folder. Those chats are visible to the folder owner and other folder members.
Which versions should be prioritized for remediation?
Open WebUI versions from 0.11.0 up to, but not including, 0.11.4 are affected. Upgrading to 0.11.4 or later removes the affected version range.