Two browser tracking firms disagree on the dominant browser, but concur that Firefox is slipping.
The New Tab feature exposes a user's travel to secure websites, but it draws the material from a source long present in the browser.
Also included in Mozilla's new mobile browser are a fresh new look, a more personalized approach, and Flash support.
Mozilla's new silent updater has not sped up the migration to Firefox 13, according to usage statistics compiled by an Irish metrics company.
The update, Flash Player 11.3.300.262, was released Thursday and applies only to Firefox on Windows.
Softly rounded tabs will feature prominently in the browser's upcoming new look.
Now in Mozilla's Aurora channel, meanwhile, Firefox 15 adds native PDF support.
The flaws were all over the map, and included memory corruption, integer and stack overflow, and security bypass bugs.
Speed, more speed, and several new features make Mozilla's free browser a must-see for users.