Convos Cross-site Scripting

Convos is an open source multi-user chat that runs in a web browser. Characters starting with "https://" in the chat window create an tag. Stored XSS vulnerability using onfocus and autofocus occurs because escaping exists for "<" or ">" but escaping for double quotes does not exist. Through this vulnerability, an attacker is capable to execute malicious scripts. Users are advised to update as soon as possible. (2022-01-04, CVE-2022-21649)

Convos is an open source multi-user chat that runs in a web browser. You can't use SVG extension in Convos' chat window, but you can upload a file with an .html extension. By uploading an SVG file with an html extension the upload filter can be bypassed. This causes Stored XSS. Also, after uploading a file the XSS attack is triggered upon a user viewing the file. Through this vulnerability, an attacker is capable to execute malicious scripts. Users are advised to update as soon as possible. (2022-01-04, CVE-2022-21650)

A Stored Cross Site Scripting (XSS) issue exists in Convos-Chat before 6.32. (2021-12-17, CVE-2021-42584)

Cross site scripting is an attack where a web page executes code that is injected by an adversary. It usually appears, when users input is presented. This attack can be used to impersonate a user, take over control of the session, or even steal API keys.

The attack can be executed e.g. when you application injects the request parameter directly into the HTML code of the page returned to the user:

https://server.com/confirmation?message=Transaction+Complete

what results in:

<span>Confirmation: Transaction Complete</span>

In that case the message can be modified to become a valid Javascript code, e.g.:

https://server.com/confirmation?message=<script>dangerous javascript code here</script>

and it will be executed locally by the user's browser with full access to the user's personal application/browser data:

<span>Confirmation: <script>dangerous javascript code here</script></span>