On Friday afternoon, Mozilla developers had posted a software patch and instructions for a workaround, both of which disable the buggy Firefox feature.

The vulnerability, which was reported to the Mozilla team earlier this week, concerns the International Domain Name (IDN) feature that Mozilla products use to process Web pages that do not use Latin Alphabet characters in their names.

Links pointing to a host with a long name composed entirely of dashes can be crafted so that Firefox will execute arbitrary code of an attacker’s choosing, meaning that an attacker theoretically could use the flaw to take control of a user’s machine.

No code that actually exploits this vulnerability has yet been seen, but all versions of Mozilla Firefox and the Mozilla Suite are affected, according to the Mozilla team.

“It’s something we take seriously because it could be used for bad things,” said Mike Schroepfer, director of engineering with the Mozilla Foundation.

Because both the patch and the workaround simply disable IDN, users who require the feature to visit international Web sites should stick to visiting Web sites they know and trust until the problem is actually repaired in the browser, Schroepfer said.

When that will happen remains unknown. “We’re determining that now,” he said.

Mozilla’s patch and workaround can be found here: http://www.mozilla.org/security/idn.html