Stored XSS in open-webui/open-webui

Vulnerability

A Stored Cross-Site Scripting (XSS) vulnerability exists in the chat file upload functionality of open-webui/open-webui version 0.3.8 [2]. The root cause is insufficient sanitization of file content, allowing an attacker to inject malicious JavaScript into a file that is later served to other users [2].

Exploitation

An attacker can upload a file containing malicious script through the chat interface. When a victim accesses the file via a shared URL or within a chat conversation, the injected JavaScript executes in the victim's browser [2]. No special privileges are required beyond the ability to upload files, making this a low-barrier attack vector.

Impact

Successful exploitation can lead to user data theft, session hijacking, malware distribution, and phishing attacks [2]. Because the XSS is stored, the malicious payload persists and can affect multiple victims over time.

Mitigation

As of the publication date, version 0.3.8 is confirmed vulnerable. Users should update to a patched version if available, and administrators may consider restricting file upload capabilities or applying input validation as a workaround [1].