Mozilla on Thursday in the United States released an update to its Firefox Web browser that fixes several security flaws and, as expected, adds support for Macs with Intel processors.

The most serious bugs in Firefox could allow an outsider to commandeer a vulnerable computer, according to the Burning Edge, a Web site that tracks development of the open-source browser.

The vulnerabilities are fixed in version 1.5.0.2, which was released on Thursday. It will be pushed out to users of Firefox 1.5 over the next two days, Mozilla, the company that oversees Firefox development, said on its Web site.

"We're identifying this as a critical release, and we're strongly recommending that everyone update as soon as possible," Mike Schroepfer, vice president of engineering at Mozilla, said in a statement.

"This is one of the most stable releases we have ever delivered. It proactively addresses a wide range of security, performance and stability issues we have identified using the very latest tools and techniques," he said.

Mozilla recommends that Firefox 1.0 users upgrade to this latest release of Firefox 1.5, it said on its Web site. The 1.5 version, released in November, includes an automated update mechanism to help people keep their systems up-to-date.

Specific information about the security holes was not immediately available on Thursday afternoon, but will be released shortly, a Mozilla representative said. The Firefox update comes two days after Microsoft released a "critical" megapatch for the rival Internet Explorer browser, fixing 10 vulnerabilities.

In addition to security patches, Firefox includes some stability enhancements and, as expected, includes native support for Apple Computer's Macs with Intel processors. Apple released the first Macs with those chips in January of this year, and Mozilla originally said it had scheduled a March release of Firefox for those machines.