Open source software company Mozilla has released an update to its browser, Firefox, to plug 12 security holes.

Version is expected to be the last tweak to this version until 2.0 emerges from beta on 26 September.

This latest version fixes various flaws including seven labelled "critical", two labelled "high" and three rated "moderate".

Some of the most important fixes are to plug a memory corruption vulnerability and to fix four JavaScript issues.

One of the vulnerabilities can be exploited by the FireSpy Trojan horse, according to security firm Sophos.

Posing as an extension to the browser, the Trojan horse goes after machines that have already been infected by the Dloadr-AKL Trojan.

You can download Firefox from Mozilla's