Firefox 3.0 recorded usage share of web browsers. Estimates of Firefox 3.0's global market share were generally in the range of 4–5%, and then dropped as users migrated to Firefox 3.5 and later Firefox 3.6. Partially as a result of this, between mid-December 2009 and the end of January 2010, Firefox 3.5 was the most popular browser (when counting individual browser versions), passing Internet Explorer 7. Mozilla ended support for Firefox 3 on March 30, 2010 with the release of 3.0.19. Firefox 3.0 was developed under the codename "Gran Paradiso". This, like other Firefox codenames, is the name of an actual place;
Firefox Institute of Standards and Technology (NIST), based on data compiled from the National Vulnerability Database (NVD), Firefox was listed as the fifth-most vulnerable desktop software, with Internet Explorer as the eighth, and Google Chrome as the first. InfoWorld has cited security experts saying that, as Firefox becomes more popular, more vulnerabilities will be found, a claim that Mitchell Baker, president of the Mozilla Foundation, has denied. "There is this idea that market share alone will make you have more vulnerabilities. It is not relational at all," she said. In October 2009, Microsoft's security engineers acknowledged that Firefox was vulnerable to