Oracle released Java 7 Update 40. Whilst there is no mention of any security flaws fixed by this new version of Java, you should probably update, (if you are running older versions like Java 6 or earlier, you should update!).
You can download Java at http://www.java.com/en/download/index.jsp or if you want to manually download Java for Windows, Mac, Linux, try http://www.oracle.com/technetwork/java/javase/downloads/jre7-downloads-1880261.html
If you have older versions of Java, you should remove them as soon as possible. The http://www.java.com/en/download/faq/remove_olderversions.xml page has more information and tools on how to remove older versions of Java.
As a additional security precaution, you can disable the execution of Java content in your browser.