According to a report by application whitelisting firm Bit9, the open source Web browser Firefox had the most security vulnerabilities in 2009.
However, Infosecurity reported that Internet Explorer wasn’t included in the study. Bit9’s criteria for inclusion in the report was stringent and IE didn’t make the grade, but the report did note that Microsoft had to patch several “zero day exploits targeting IE 6 and 7 in 2009.”
The security problems with Firefox included the ability to run arbitrary Javascript, according to Infosecurity.
