Java 1.7 Critical Vulnerability
A vulnerability is actively being exploited for Java 1.7 update 6 for all web browsers for all operating systems. A patch has been released for this vulnerability and you should update to the latest version of Java as soon as possible.
An alternative is to disable Java in your web browser.
Disable Java plug-in for most popular browsers/operating systems: http://krebsonsecurity.com/how-to-unplug-java-from-the-browser/
Suggested reading on the topic: