The upgrade also lets users set an option that loads plug-ins -- such as Adobe's Flash Player or Oracle's Java -- only after approval, an additional security measure that may prevent stop some attacks.
Half of the 18 bugs quashed in Firefox 14 were rated "critical" by Mozilla, while four were labeled as "high" threats in the company's four-step scoring system. The remaining five were pegged as "moderate" vulnerabilities.
, uncovered by a Mozilla security researcher, involved the "javascript:" URL format, which could be exploited by attackers to escape from the JavaScript "sandbox," an anti-exploit technology designed to safely execute scripting code.
Three of the 18 flaws were reported by Google security engineers, and several bugs that could be used to conduct phishing attacks were also crushed in the upgrade to Firefox 14.
All 18 vulnerabilities were also patched in a companion update to the Firefox ESR, or Extended Support Release, version of the browser. Firefox ESR is designed for businesses that run the open-source browser; unlike the normal build, it doesn't change its feature set or user interface (UI) for over a year, and only receives security patches.
on June 5. The company issues a new version every six weeks under the rapid-release schedule it adopted last year.
That schedule was criticized earlier this month by Jono Xia, a five-year veteran of the firm. in general, and those by Mozilla specifically, in a blog post that attracted widespread attention.
Xia's contention was that updates are major disruptions, and that developers do not properly weigh users' concerns about dealing with constantly-changing software.
Feature changes to Firefox 14 included support for OS X Lion's full-screen mode, work that started in March 2011; so-called "click-to-play" plug-ins that require the user to authorize any plug-in execution by clicking on a page component; and a by-default secure connection between the browser and Google's search site.
The latter, said Mozilla, encrypts the data sent to google.com to keep it from being spied on by "prying eyes, like network administrators when you use public or shared WiFi networks."
The automatic encryption of searches sent to Google, however, does not prevent Google from disabling the protection when users click advertisements on the ensuing search results page, noted search expert Danny Sullivan, who operates the website.
Enable Click-to-Play in Firefox 14, and you must approve plug-ins, such as Java or Flash, before they're allowed to run. In this example from the New York Times site, the plug-in content is defined by the large gray box in the middle of the page.
Click-to-play, which has been in development for several months, remains off by default in Firefox 14. To turn it on, users must enter "about:config" in the browser's address bar, click the "I'll be careful, I promise" button, then search the configuration file for the phrase "plugins.click_to_play" and finally double-click that item to change the value from "false" to "true."
According to Web analytics company Net Application, Firefox users accounted for 20.1% of all those who went online last month, a slight uptick from the record low of 19.7% the month before. Irish measurement firm StatCounter, meanwhile, pegged Firefox's global share in June at 24.6%, a full percentage point lower than in May.
Windows, Mac and Linux editions of can be downloaded manually from Mozilla's site. Installed copies will be upgraded automatically.
The next version of Firefox is scheduled to ship August 28.
Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at , on or subscribe to . His email address is .
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