Ticket #9873: 9873.patch

wp-includes/default-constants.php

@@ -226 +226 @@
         /**
          * @since 2.0.0
          */
-        if ( !defined('COOKIE_DOMAIN') )
-                define('COOKIE_DOMAIN', false);
+        if ( ! defined( 'COOKIE_DOMAIN' ) ) {
+                $cookie_domain = false;
+                $home_host = parse_url( home_url(), PHP_URL_HOST );
+                $site_host = parse_url( site_url(), PHP_URL_HOST );
+                if ( $home_host !== $site_host && str_replace( 'www.', '', $home_host ) === str_replace( 'www.', '', $site_host ) )
+                        $cookie_domain = str_replace( 'www.', '', $site_host );
+                define( 'COOKIE_DOMAIN', $cookie_domain );
+        }
 }
 
 /**