"In 2008, Firefox faced 115 reported security flaws, which is
nearly four times as many as any other popular web browser.
Microsoft, Apple, and Opera respectively reported 31, 32, and 30
security flaws in their browser. It is valuable to note, though,
that Firefox is an open-source product, and therefore, security
flaws may be be dragged kicking and screaming into the light of day
easier than with its closed-source brethren. Still, if that can
account for such a major difference is debatable, at best."