@lex Guestbook 4.0.5 - 'index.php?test' Cross-Site Scripting

source: https://www.securityfocus.com/bid/28519/info
 
@lex Guestbook is prone to multiple cross-site scripting vulnerabilities because it fails to properly sanitize user-supplied input.
 
An attacker may leverage these issues to execute arbitrary script code in the browser of an unsuspecting user in the context of the affected site. This may allow the attacker to steal cookie-based authentication credentials and to launch other attacks.
 
@lex Guestbook 4.0.5 is vulnerable; other versions may also be affected.
 
UPDATE (April 25, 2008): The vendor indicates that the 'test' parameter is a user-defined parameter and is not vulnerable. 

http://www.example.com/alexguestbook4/index.php?mots_search=&rechercher=Ok&debut=0(=&skin=&test="><script>alert()</script>