source: https://www.securityfocus.com/bid/8956/info

It has been reported that Sympoll is prone to a cross-site scripting vulnerability. The issue is reported to exist due insufficient sanitization of user-supplied data through the 'vo' parameter. The problem may allow a remote attacker to execute HTML or script code in the browser of a user following a malicious link created by an attacker.

Successful exploitation of this attack may allow an attacker to steal cookie-based authentication information that could be used to launch further attacks.

Sympoll version 1.5 is reported to be prone to this issue, however other versions may be affected as well.

http://www.example.com/index.php?vo="><script>alert(document.cookie);</script>