Microsoft has published patches for a flurry of security vulnerabilities residing within SQL Server 2000, Exchange Server, and Metadirectory Services 2.2. The company gave the flaw in SQL Server 2000 a "critical" rating. The others it considers "moderate."

SQL Server actually has multiple flaws. One is in a feature that enables a single server to run concurrent sessions of the database and makes it possible for attackers to launch denial-of-service attacks. Two other SQL flaws are buffer overflows, making it possible for attackers to crash the server and add an application of their choice to the database.

Patches for the critical flaw in SQL Server, as well as the flaws in Exchange Server and Metadirectory, can be found at www.microsoft.com/security.