    public static function header($vars=""){
        header("Cache-Control: must-revalidate,max-age=300,s-maxage=900");
        $offset = 60 * 60 * 24 * 3;
        $ExpStr = "Expires: " . gmdate("D, d M Y H:i:s", time() + $offset) . " GMT";
        header($ExpStr);
        header("Content-Type: text/html; charset=utf-8");

        if (isset($vars)) {
            # code...
            $GLOBALS['data'] = $vars;
            self::theme('header', $vars);
        }else{
            self::theme('header');
        }

    }

The software constructs all or part of an SQL command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended SQL command when it is sent to a downstream component.