Mozilla developers have released an update to its popular open source browser to address several security and stability issues in previous versions. Specifically, Firefox 3.0.6 fixes six vulnerabilities, one of which is rated as critical and relates to the browser’s JavaScript and layout engines that could be exploited by attackers to run unauthorized software on a victim’s machine.

A vulnerability in Mozilla’s SessionStore feature was also repaired along with other less critical flaws that include a chrome privilege escalation attack method using local desktop shortcut files, a XML request error and a cached pages problem. The update also fixes a reported issue which caused parts of a screen to be improperly displayed after Firefox has been running for a long time. You can find a complete list of changes in this page and a download link over here.

This comes as Firefox's market share has gone up 3% in ten months to about 21%, while Microsoft's dominant Internet Explorer has slipped below the 70% mark according to a recent survey.