Is there a risk of having xmlrpc.php on my site?
You are save. At least to what we know now.

The first linked article is wordpress related. This is totally different code. Not drupal related at all!


  Drupal had a known security flaw in versions lower than 6.38 / 7.43 /
  8.04


So your version 7.56 is patched. Always make sure to update to the latest version and you're good.