Open WebUI is an extensible, feature-rich, and user-friendly self-hosted AI platform. Prior to 0.10.0, Open WebUI runs client-side Python with Pyodide in a same-origin web worker, allowing stored chat payloads that use pyodide.http.pyfetch or the js module fetch and XMLHttpRequest APIs to issue authenticated same-origin requests when a victim clicks Run, which can reach admin-only endpoints and execute server-side code through configured tools. This issue is fixed in version 0.10.0.

Open WebUI: Stored web worker XSS via Pyodide