Considering security and risk level, I would like to suggest you to use Security AppScan software which helps to test this vulnerability . Also, it will help you to identify other vulnerability present in your system.The below article says how to use the AppScan software.
Just a description of the vulnerability in your system
Cross Site Scripting enables attackers to inject client-side scripts into web pages viewed by other users. The malicious script can access any cookies, session tokens, or other sensitive information retained by the browser and used with that site. These scripts can even rewrite the content of the HTML page.