A security release for WordPress is out today and it is highly suggested that you upgrade. This is two major security fixes from the WordPress team in recent months. Props goes out to Matt and the rest of the team for staying on top of this. The note from the WordPress site is below.
We would like to announce that WordPress 18.104.22.168 is now released as we continue the availablity of a highly stable and extremely popular branch based on the 1.5 Strayhorn codebase. Development has moved on to some exciting new features for the next major release, but an important security issue was brought to our attention which required an update for our users. The problem is not yet public but you should update your blog as soon as possible to 22.214.171.124. If you are unable to do upgrade in the short-term you may protect yourself by deleting the xmlrpc.php file from your WordPress directory.