The vulnerability stems from the use of SQLite’s SQL LIKE operator to match OAuth subject claims in Open WebUI. Wildcard characters such as percent and underscore in the OAuth subject can match unintended user records, allowing an attacker to sign in as an administrator or any privileged user. This bypasses the intended authentication flow, corresponding to CWE-287 for authentication bypass and CWE-155 for unintended disclosure.

Open WebUI versions from 0.6.41 up to and including 0.11.1 are affected when using SQLite. Deployments that use PostgreSQL are not impacted. The issue is internal to the get_user_by_oauth_sub and get_user_by_scim_external_id functions in the user model.

The CVSS score of 8.1 classifies the vulnerability as high severity. EPSS is not available, and the vulnerability is not listed in the CISA KEV catalog, suggesting a moderate likelihood of exploitation at present. The likely attack vector is a compromised or malicious OAuth provider that can supply a crafted subject claim containing wildcard characters. Successful exploitation results in full account impersonation and immediate privilege escalation for the attacker.