Sucuri has released an urgent security advisory for WP Super Cache. This is a very popular WordPress plugin. Details of the vulnerability can be found here:

http://blog.sucuri.net/2015/04/security-advisory-persistent-xss-in-wp-super-cache.html

All sites using WP Super Cache are advised to upgrade immediately.

If you are subscribed to Reliable Penguin's Managed WordPress service then your sites have already been upgraded if necessary. 

If you need assistance with this upgrade please contact support at 866-649-7984 or support@reliablepenguin.com