            $q = self::$mysqli->query($vars) ;
            if($q === false) {
                Control::error('db',"Query failed: ".self::$mysqli->error."<br />\n"); 
            }
        }
        
        return $q;
    }
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.