sanitize all dangerous superglobals

index.php

foreach ($_GET as $key => $value) {
	$_GET[$key] = filter_input(INPUT_GET, $key, FILTER_SANITIZE_STRING);
}

foreach ($_POST as $key => $value) {
	$_POST[$key] = filter_input(INPUT_POST, $key, FILTER_SANITIZE_STRING);
}

foreach ($_COOKIE as $key => $value) {
	$_COOKIE[$key] = filter_input(INPUT_COOKIE, $key, FILTER_SANITIZE_STRING);
}

foreach ($_SERVER as $key => $value) {
	$_SERVER[$key] = filter_input(INPUT_SERVER, $key, FILTER_SANITIZE_STRING);
}

foreach ($_ENV as $key => $value) {
	$_ENV[$key] = filter_input(INPUT_ENV, $key, FILTER_SANITIZE_STRING);
}

$_REQUEST = array_merge( $_GET, $_POST );