        foreach ($aIP as $piece)
        {
                if (!preg_match('#^[0-9a-fA-F]{4}$#s', sprintf('%04s', $piece)))
                {
                        return false;
                }
        }
The software does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.