Most browser installations use outdated versions of the Java plug-in that are vulnerable to at least one of several exploits currently used in popular Web attack toolkits, according to statistics ...

However, Websense’s data shows that a large number of Java-enabled browser installations are also vulnerable to exploits used in much cheaper and widespread exploit kits.

The Java telemetry data gathered by Websense showed that only 5.5 percent of Java-enabled browsers have the most up-to-date versions of the software’s browser plug-in — Java 7 Update 17 (7u17 ...

This can be exploited to execute arbitrary code when a user visits a malicious web site using a Java-enabled browser e.g. Safari or Firefox." ...

But you may want to avoid installing Java or at least disable it in your Web browser. Java came pre-installed and enabled in earlier versions of PCs and Mac operating systems.