Firefox 1.0.2 addresses a problem in the browser's handling of animated GIF images. A malicious hacker could exploit the vulnerability, by creating a carefully crafted GIF file that when viewed by the browser would execute malicious code on the computer. 

"There's a lot of discussion on the internet at the moment as to which web browser offers the highest level of security. What's clear is that everyone who uses the internet has to make sure they stay up-to-date with the latest security fixes. The increasing popularity of Firefox will undoubtedly mean that its users will be targeted by more hackers in the future," said Graham Cluley, senior technology consultant for Sophos. "With organised crime increasingly attempting to steal from innocent users through viruses, phishing attacks and malicious spyware, no-one can afford to relax when it comes to security."

More information about the new version of Firefox, which is available for Windows, Mac OS X and Linux, can be found on Mozilla's website.

Firefox is said to have been downloaded by over 30 million people, and has stolen market share from the leading web browser, Microsoft's Internet Explorer.

Sophos continues to recommend computer users practise safe computing as well as running up-to-date anti-virus software.