Critical flaw found in Firefox 3.5

 

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By Nicole Kobie

Posted on 15 Jul 2009 at 17:13

A newly-discovered critical flaw in Firefox 3.5's JavaScript compiler could be used to execute malicious code, Mozilla developers have admitted.

According to the Mozilla security blog, the vulnerability in the Just-in-time JavaScript compiler was discovered last week - just over a week after Firefox 3.5 was made available for download. The TraceMonkey JavaScript engine has been patched once already.

"Mozilla developers are working on a fix for this issue and a Firefox security update will be sent out as soon as the fix is completed and tested," Mozilla noted on its security blog.

In the meantime, users can either run Firefox in Safe Mode or disable the compiler. Mozilla provides instructions on disable the compiler on its security blog, but acknowledges that this will hurt JavaScript performance.

The flaw can only be exploited if a Firefox user visits a web page containing malicious code.