Users of recent Firefox versions may have received notices, but those still using older versions may have missed out:

[From eWeek]

New Firefox Updates Eliminate Major Security Flaw
February 23, 2007
By Chris Preimesberger

Mozilla on Feb. 23 released updated versions of the Firefox browser, v1.5.0.10 and v2.0.0.2, for Windows, Mac and Linux, which include the fix for a major security flaw.

The "location.hostname" vulnerability potentially allowed hackers to tamper with authentication cookies for third-party sites, manipulating how Web sites are displayed and how they operate, Mozilla said.

"We strongly recommend that all Firefox users upgrade to this latest release," said Mike Schroepfer, vice president of engineering for Mozilla, in Mountain View, Calif.

"This update resolves the location.hostname vulnerability, and other security and stability issues. Thanks to the work of our contributors, we have been able to address these issues quickly in order to minimize the security risk to Firefox users."

The updates are available immediately in 37 languages, including French, German, Spanish, Italian and Japanese.

Other security fixes in the new versions, according to Schroepfer, include improvements to help protect against cross-site scripting attacks; an adjustment of Mozilla Network Security Services SSLv2 to stop buffer overflow; the fixing of XSS and local file access by opening blocked popups; the elimination of spoofing using custom cursor and CSS3 hotspot; and the elimination of information disclosure through cache collisions.

For details on which flaws were fixed in this release, click here.

Firefox 1.5.0.x will be maintained with security and stability updates until April 24, 2007; however, all users are encouraged to upgrade to Firefox 2, Schroepfer said.
Users who already have Firefox 1.5.0.x or Firefox 2.0.0.x will receive an automated update notification within 24 to 48 hours, Schroepfer said. This update can also be applied manually by selecting "Check for Updates" from the Help menu starting later in the day on Feb. 23, Schroepfer said.

The new Firefox v2.0.0.2 update can be obtained here. Firefox v1.5.0.10 is available for download here.

Click here to read more about the location.hostname vulnerability, and how it could be used to make a malicious site appear authentic.

For "a pending issue:" Click here to read about a critical memory corruption flaw that wasn't addressed by this update.

[end eWeek quotes]

Some of the "other things" fixed in this release appear to be somewhat like things that have caused significant problems with "the other browser," so this should be considered a "significant upgrade."

The eWeek article at the first link above offers a number of "related info" links that may be of interest; but I'll leave it for those adventurous enough to find them (it's not too hard). For those really interested, the Security Watch blog might be a good bookmark to have handy to keep an eye on things.

John