Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to version 0.6.6, a vulnerability in the way certain html tags in chat messages are rendered allows attackers to inject JavaScript code into a chat transcript. The JavaScript code will be executed in the user's browser every time that chat transcript is opened, allowing attackers to retrieve the user's access token and gain full control over their account. Chat transcripts can be shared with other users in the same server, or with the whole open-webui community if "Enable Community Sharing" is enabled in the admin panel. If this exploit is used against an admin user, it is possible to achieve Remote Code Execution on the server where the open-webui backend is hosted. This can be done by creating a new function which contains malicious python code. This vulnerability also affects chat transcripts uploaded to `https://openwebui.com/c/<user>/<chat_id>`, allowing for wormable stored XSS in https[:]//openwebui[.]com. Version 0.6.6 contains a patch for the issue.
An XSS vulnerability exists in open-webui/open-webui versions <= 0.3.8, specifically in the function that constructs the HTML for tooltips. This vulnerability allows attackers to perform operations with the victim's privileges, such as stealing chat history, deleting chats, and escalating their own account to an admin if the victim is an admin.