There have been numerous reports of new exploit within Internet Explorer. If you use IE be mindful that until the update to fix the patch has been released you are at risk. Consider using Google Chrome or Mozilla Firefox. Also for existing Windows XP users there will not be a patch released so if you need to upgrade your PC now is the time to do it.
http://money.cnn.com/2014/04/28/technology/security/internet-explorer-bug/index.html