Admidio Cross-site Scripting

Admidio 4.1.2 version is affected by stored cross-site scripting (XSS). (2022-06-28, CVE-2022-23896)

Admidio is a free open source user management system for websites of organizations and groups. A cross-site scripting vulnerability is present in Admidio prior to version 4.0.12. The Reflected XSS vulnerability occurs because redirect.php does not properly validate the value of the url parameter. Through this vulnerability, an attacker is capable to execute malicious scripts. This issue is patched in version 4.0.12. (2021-12-07, CVE-2021-43810)

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>