The Mozilla Foundation has released a security patch to plug two security flaws in its popular Firefox browser.

The flaws were found last week by security firm Secunia who deemed them "extremely critical." Mozilla recommends users upgrade to the latest version, Firefox 1.0.4, which is primarily a security update.

Earlier this week, Secunia announced it had found several security flaws in the browser. According to Secunia, two vulnerabilities found in the increasingly popular browser can be exploited to conduct cross-site scripting attacks and compromise a user"s PC. Cross-site scripting (also known as XSS) occurs when a Web application gathers malicious data from a user. Many security experts have speculated that, as Firefox gains in popularity, it too will be hit by hackers much like Microsoft"s Internet Explorer.

Firefox is Microsoft"s main rival in the browser market. Since launching late last year, Firefox has had more than 50 million downloads.

IE has an 88.9 percent share of the browser market, according to net monitoring company WebSideStory, whereas Firefox"s share is 6.8 percent. Microsoft plans to release a more secure version of IE this summer.