This release patched virtually the same number of vulnerabilities as the last security upgrade seven weeks ago.
Firefox 3.0.4, the fourth update since Mozilla launched the browser in June, fixes six flaws marked 'critical', two 'high', two 'moderate', and one 'low' in Mozilla's four-step scoring system. Most of the critical bugs could be used by hackers to introduce their own malicious code into a vulnerable system.
Mozilla repeatedly patched protocol handler bugs in Firefox starting in July 2007. That vulnerability was judged moderate by Mozilla because of extenuating circumstances.
"It requires an attacker to have malicious code saved locally, then have a user open a chrome: document or privileged about: URI, and then open the malicious file in the same privileged tab," Mozilla said in its advisory.
Mozilla also updated the nearly-retired Firefox to 188.8.131.52, patching all but two of the same vulnerabilities fixed in 3.0.4, and several others for good measure. Of the dozen bugs, six were rated critical. The 184.108.40.206 update will be the next-to-last for the older Firefox 2.0, which will be dropped from support next month.
Before that happens, Mozilla will make one last effort to convince Firefox 2.0 users to upgrade. In two to three weeks users will again be prompted to upgrade in a repeat of an offer first extended in August. Mozilla has been very successful in convincing users to upgrade; as of the end of October, 73 percent of users were running the newer Firefox 3.0, reported web metrics firm Net Applications.
At times, the gap between Firefox and Thunderbird patches has been more than a month. This time, however, Thunderbird should be updated soon; version 220.127.116.11 entered beta test this week.
Users can download the update for Windows, Mac OS X and Linux from the Mozilla site, call up their browser's built-in updater or wait for the automatic update notification, which typically appears within 48 hours.