Xpressengine Cross-site Scripting

In XE 1.116, when uploading the Normal button, there is no restriction on the file suffix, which leads to any file uploading to the files directory. Since .htaccess only restricts the PHP type, uploading HTML-type files leads to stored XSS vulnerabilities. If the .htaccess configuration is improper, for example before the XE 1.11.2 version, you can upload the PHP type file to GETSHELL. (2022-02-09, CVE-2021-44912)

XE before 1.11.6 is vulnerable to Unrestricted file upload via modules/menu/menu.admin.controller.php. When uploading the Mouse over button and When selected button, there is no restriction on the file suffix, which leads to any file uploading to the files directory. Since .htaccess only restricts the PHP type, uploading HTML-type files leads to stored XSS vulnerabilities. (2022-02-09, CVE-2021-44911)

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>