source: https://www.securityfocus.com/bid/5890/info

Reportedly, phpLinkat is prone to cross site scripting attacks.

An attacker may exploit this vulnerability by enticing a victim user to follow a malicious link containing HTML and script code. The attacker-supplied HTML and script code may be executed on a web client in the context of the site hosting phpLinkat.

Attackers may potentially exploit this issue to manipulate web content or to steal cookie-based authentication credentials. It may be possible to take arbitrary actions as the victim user.

http://target/showcat.php?catid=<Script>JavaScript:alert('test');</Script>

http://target/addyoursite.php?catid=<Script>JavaScript:alert('test');</Script>