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The Mozilla Foundation has released a new version of its Firefox browser that contains fixes for two critical security bugs in the software that were reported over the past week.

The most widely reported flaw concerns the International Domain Name (IDN) feature that Mozilla products use to process Web pages that do not use the Latin alphabet.

Links pointing to a host with a long name composed entirely of dashes can be crafted so that earlier versions of Firefox will execute arbitrary code of an attacker's choosing. This means that an attacker theoretically could use the flaw to take control of a user's machine, by launching what is called a buffer overflow attack.

Quick Response

Firefox 1.0.7, which was released Wednesday morning, also fixes a critical flaw in the way the Mozilla software handles Unix and Linux shell commands that could allow attackers to run unauthorized software on some systems, said Chris Beard, head of products with Mozilla.

All Firefox users are encouraged to download the new release, which also contains a number of minor changes designed to make the browser more stable and secure, Beard said.

The IDN bug was discovered by security researcher Tom Ferris and made public via a posting to the Full Disclosure security mailing list last Friday. By the end of the day, Mozilla had published a workaround, which disabled the IDN feature. With the 1.0.7 release, this problem has now been rectified, Beard said.

Mozilla is planning a similar update for its Mozilla Suite browser, Beard said. That software is expected to be released by week's end.

Mozilla is also testing an update to the browser, which is available as a beta and will ship as Firefox 1.5.