Zero-day in the wild, in a popular exploit kit.

From Brian Krebs:

The hackers who maintain Blackhole and Nuclear Pack – competing crimeware products that are made to be stitched into hacked sites and use browser flaws to foist malware — say they’ve added a brand new exploit that attacks a previously unknown and currently unpatched security hole in Java.

Alienvault confirms:

Earlier this morning @Kafeine alerted us about a new Java zeroday being exploited in the wild. With the files we were able to obtain we reproduced the exploit in a fully patched new installation of Java. As you can see below we tricked the malicious Java applet to execute the calc.exe in our lab.

To the best of your ability, disable Java in browsers and keep it that way. Otherwise you need alternate compensating controls. No idea if EMET helps with this, but that’s one place to start looking.