Open WebUI versions prior to 0.7.0 are vulnerable to a stored cross-site scripting (XSS) attack via the iFrame in the citations model. This occurs because users can manually modify chat history to set the 'html' property in document metadata, causing the frontend to render untrusted HTML content inside an iFrame with insufficient sandboxing. The vulnerability allows execution of arbitrary JavaScript when the citation is previewed or viewed in a shared chat. Exploitation requires the victim to expand the sources and click the malicious document. This can lead to session token theft for low-privilege users and potential remote code execution (RCE) risks for admins when combined with another vulnerability. No official patch or fix is currently documented.