For the fourth time in three months, <A HREF="http://www.eweek.com/article2/0,1759,1814056,00.asp">major security flaws in the Firefox Web browser</A> have pushed volunteers at the Mozilla Foundation into damage-control mode. The open-source group late Sunday rushed out a partial fix for a pair of "extremely critical" Firefox vulnerabilities after zero-day exploit code leaked onto the Internet and promised a comprehensive patch would be available soon. Mozilla's public acknowledgment of the vulnerabilities includes a chilling warning that an attacker could combine the flaws to execute malicious code without user interaction.