Fix: compatibility with proxies that extends HTTP_X_FORWARDED_HOST

Author: pitbulk

src/Saml2/Utils.php

@@ -511,7 +511,7 @@ protected static function getRawHost()
         if (self::$_host) {
             $currentHost = self::$_host;
         } elseif (self::getProxyVars() && array_key_exists('HTTP_X_FORWARDED_HOST', $_SERVER)) {
-            $currentHost = $_SERVER['HTTP_X_FORWARDED_HOST'];
+            $currentHost = explode(',', $_SERVER['HTTP_X_FORWARDED_HOST'])[0];
         } elseif (array_key_exists('HTTP_HOST', $_SERVER)) {
             $currentHost = $_SERVER['HTTP_HOST'];
         } elseif (array_key_exists('SERVER_NAME', $_SERVER)) {