Security problems with Microsoft's dominant Internet Explorer browser helped pave the way for Mozilla Firefox to emerge as an alternative for Web surfers.

However, Firefox users should be aware that hackers can exploit software flaws and design features to launch attacks.

The following configuration changes, recommended by CERT/CC, can disable various features and set up the browser to run in a secure state, limiting the damage from malware attacks.

http://content.zdnet.com/2346-12691_22-93923.html

still, IE is the most vulnerable browser. However, it is a good article for firefox security