source: http://www.securityfocus.com/bid/25699/info

b1gMail is prone to a cross-site scripting vulnerability because it fails to properly sanitize user-supplied input.

Exploiting this vulnerability may allow an attacker to perform cross-site scripting attacks on unsuspecting users in the context of the affected website. As a result, the attacker may be able to steal cookie-based authentication credentials and to launch other attacks.

b1gMail 6.3.1 is vulnerable; other versions may also be affected. 

http://www.example.com/hilfe.php?chapter="+onmouseover=alert(1898233298)+