-3.9.1WordPress 3.8.x-3.8.3WordPress 3.7.x-3.7.3WordPress 3.6.xWordPress 3.5.x
How to fix
Delete xmlrpc.php from the WordPress root directory.
Upgrade WordPress to the latest official version.
...
adding permission authentication or specifying the IP addresses that are allowed to access it.
If you do not need to use the page, we recommend that you delete it.
...