We know there is a Java problem — most security experts agree with Sophos’ security expert, Paul Ducklin, who has consistently told computer users on any platform to “ switch Java off “.

Apple has released a software update after the company admitted a security flaw had left its own employees' computers exposed to hackers.

Almost every Mac is running Apple's version of Java 1.6, and almost every Linux box is running OpenJDK, neither of which are vulnerable to this exploit.