The Amelia WordPress plugin is vulnerable to Cross-Site Scripting due to insufficient escaping and sanitization of the lastName parameter found in the ~/src/Application/Controller/User/Customer/AddCustomerController.php file which allows attackers to inject arbitrary web scripts onto a pages that executes whenever a user accesses the booking calendar with the date the attacker has injected the malicious payload into. This affects versions up to and including 1.0.46.
The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.