Youzify Cross-site Scripting

The About Me widget of the Youzify – BuddyPress Community, User Profile, Social Network & Membership WordPress plugin before 1.0.7 does not properly sanitise its Biography field, allowing any authenticated user to set Cross-Site Scripting payloads in it, which will be executed when viewing the affected user profile. This could allow a low privilege user to gain unauthorised access to the admin side of the blog by targeting an admin, inducing them to view their profile with a malicious payload adding a rogue account for example. (2021-08-02, CVE-2021-24443)

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>