Mozilla patches Firefox JavaScript bug

by Gregg Keizer

April 17, 2008 —

Mozilla on Wednesday
patched a single critical security vulnerability in the JavaScript engine of
Firefox,
updating the open-source browser to Version 2.0.0.14.

According to the associated advisory, Mozilla patched the bug primarily for
stability reasons, but said that attackers might leverage crashes in JavaScript's
garbage collector. "We have no demonstration that this particular crash
is exploitable but are issuing this advisory because some crashes of this type
have been shown to be exploitable in the past," the advisory
read.

JavaScript's garbage collector reclaims memory and returns it to the system;
its efficiency is an important factor in the performance of JavaScript specifically
and Firefox in general.

Firefox 2.0.0.14 can be downloaded
from the Mozilla site in versions for Windows, Mac
OS X and Linux. Users running Firefox can call up the browser's built in
updater, or wait for the automatic update notification, which typically appears
within 24 to 48 hours after Mozilla posts a new version.

As with Firefox fixes issued in March, Wednesday's wasn't added to Thunderbird,
even though the e-mail client uses Firefox's engine. A month ago, David Ascher,
the head of Mozilla Messaging Inc. pleaded
lack of resources when he explained why JavaScript bugs in Thunderbird weren't
fixed, but said the e-mailer would be patched in "several weeks."

Thunderbird has not been updated since early February.

Wednesday, Mozilla again warned Thunderbird users that JavaScript was potentially
dangerous because patches hadn't been applied. "Thunderbird shares the
browser engine with Firefox and could be vulnerable if JavaScript were to be
enabled in mail," the advisory said. "This is not the default setting
and we strongly discourage users from running JavaScript in mail."

Computerworld