CVE-2026-56398

Name of the Vulnerable Software and Affected Versions Open WebUI versions prior to 0.9.5

Description A stored cross-site scripting issue exists in the OAuth authentication flow. The system infers the MIME type of the picture claim URL from the file extension instead of the Content-Type header, which allows SVG files to bypass the profile image validator and be stored as data URIs. When authenticated users access the profile image endpoint, they receive attacker-controlled SVG content. Due to the lack of default security headers and the use of inline disposition, scripts can be executed within the same origin, potentially leading to the theft of authentication tokens and account takeover.

Recommendations Update Open WebUI to version 0.9.5 or later.