Open WebUI Socket.IO Session Privilege Escalation Vulnerability

A vulnerability in Open WebUI versions prior to 0.9.0 allows users to retain administrative privileges in their Socket.IO sessions even after their roles have been revoked. This issue arises because changes to user roles and deletions are not reflected in the session pool, allowing former admins to bypass access controls in real-time collaborative features.

Impact

Exploitation of this vulnerability allows a user to read and write notes belonging to other users, bypassing normal access controls. The vulnerability takes advantage of stale role information in the Socket.IO session cache, which can be exploited for as long as the connection remains active.

Reproduction

To reproduce this vulnerability, first, connect to the Open WebUI application as a user with admin privileges. Once the Socket.IO session is active, have an admin revoke the user's privileges or delete the user entirely. Despite the role change or deletion, the Socket.IO session will not be updated, allowing the user to continue accessing and modifying notes in real-time collaboration features as if they were still an admin.

Remediation

Users can update to Open WebUI version 0.9.0 or later, where this vulnerability has been fixed.