Mozilla's latest version of Firefox addresses a critical security flaw that was recently discovered at the 2010 Pwn2Own contest by security researcher Nils of MWR InfoSecurity. The flaw, which existed only in version 3.6 and later, was related to memory corruption via "re-use of a freed object due to scope confusion," and could have led to an attacker running arbitrary code on a victim's computer. (Free, 19 MB)