Ryan Naraine - eWEEK The Microsoft security train made its scheduled monthly stop on Tuesday, dropping off eight updates to cover 18 vulnerabilities in a range of widely deployed products. Five of the eight advisories are rated "critical" and Redmond officials are urging customers to apply at least three immediately as high-priority updates. The top three include fixes for high-risk flaws in Microsoft Corp.'s implementation of the TCP/IP stack; a cumulative patch for the Internet Explorer browser; and a patch for a remote code-execution hole in the enterprise-focused Microsoft Exchange Server.