Open WebUI from 0.11.1 before 0.11.4 contains an authorization bypass in the OAuth token exchange endpoint, which reads role claims only from the… (CVE-2026-109283)

The vulnerability in Open WebUI versions >=0.11.1 <0.11.4 is an authorization bypass in the OAuth token exchange endpoint (/api/v1/auths/oauth/{provider}/token/exchange). The endpoint incorrectly bases role claims solely on the provider's userinfo response and does not consider roles sent exclusively in the ID token. When no roles claim is found in the userinfo response, the system retains the user's existing role rather than enforcing updated role policies. This allows an attacker with a linked account and a valid provider access token to maintain a session with a previously assigned role that may no longer be authorized according to the current OAuth role policy.

An attacker with a linked account and a valid provider access token can bypass updated OAuth role policies by retaining a previous role that may grant elevated privileges. This results in a partial authorization bypass, potentially allowing unauthorized access or actions within the application. The CVSS score of 5.4 (medium severity) reflects limited confidentiality and integrity impact with no availability impact.

A fix is available in Open WebUI version 0.11.4 that addresses this authorization bypass. Users should upgrade to version 0.11.4 or later to remediate this vulnerability. No additional mitigations are specified. Patch status is confirmed by the version range indicating the fix in 0.11.4.