source: https://www.securityfocus.com/bid/18857/info

ATutor is prone to multiple cross-site scripting vulnerabilities. These issues are due to a failure in the application to properly sanitize user-supplied input.

An attacker may leverage any of these issues to have arbitrary script code execute in the browser of an unsuspecting user in the context of the affected site. This may help the attacker steal cookie-based authentication credentials and launch other attacks.

Versions 1.5.1 and 1.5.3 RC2 are vulnerable; other versions may also be affected.

http://www.example.com/users/browse.php?cat=[code]