Index: wp-admin/admin-post.php
===================================================================
--- wp-admin/admin-post.php	(revision 24433)
+++ wp-admin/admin-post.php	(working copy)
@@ -14,6 +14,9 @@
 else
 	require_once('../wp-load.php');
 
+/** Allow for cross-domain requests (from the frontend). */
+send_origin_headers();
+
 require_once(ABSPATH . 'wp-admin/includes/admin.php');
 
 nocache_headers();