Mozilla on Wednesday patched 10 security vulnerabilities in Firefox 3.5, all but one ranked critical, as it delivered the first update that automatically checks for outdated versions of the popular Flash Player plug-in.

Mozilla late on Thursday began offering Firefox 3.5 to users still running older versions of the browser, the first of what will likely be several attempts to get people to upgrade before support expires for Firefox 3.0.

Mozilla today patched Firefox 3.5 and Firefox 3.0 to quash three security vulnerabilities, including a pair unveiled last week at Black Hat, and a third Mozilla itself revealed last month.

Mozilla last week issued the first patch for Firefox 3.5, fixing a flaw that went public Monday. One noted contributor had called the flaw a "self-inflicted" vulnerability.

Mozilla yesterday confirmed the first security vulnerability in Firefox 3.5, and said that the bug could be used to hijack a machine running the company's newest browser.

A critical flaw in the way Firefox 3.5 handles Javascript opens the door to a serious attack, according to Secunia, which tracks security vulnerabilities.

Mozilla will patch the just-released Firefox 3.5 in the next few weeks to stamp out several bugs that went unfixed in the final version of the browser, the company said Tuesday.

The latest release of Firefox appeared as promised this afternoon BST on the Mozilla website, with the headline improvement being a claimed performance boost. It also comes with some bugs.

While Mozilla lights a fire under competing browsers with support of emerging Web standards with Firefox 3.5, it can still improve its performance, reliability, and usability.