source: https://www.securityfocus.com/bid/59041/info

Hero is prone to multiple cross-site scripting vulnerabilities because it fails to sufficiently sanitize user-supplied input.

Exploiting these issues could allow an attacker to steal cookie-based authentication credentials, compromise the application, access or modify data, or exploit latent vulnerabilities in the underlying database.

Hero 3.791 is vulnerable; other versions may also be affected. 

http://www.example.com/users/login?username=%22%3E%3Cscript%3Ealert%28document.cookie%29;%3C/script%3E