The "critical" patches address vulnerabilities in Internet Explorer (IE) and Microsoft Exchange Server, while the fixes labeled "important" involve bugs in SQL Server and Visio, a drawing software product.
The IE issue, though, only is "critical" in Windows XP and Vista, while it is labeled "moderate" in Windows Server 2003 and 2008. The Exchange issue is "critical" for all supported editions: 2000, 2003 and 2007.
Corey Thomas, vice president of product management at vulnerability assessment firm Rapid7, said he would not be surprised if more Exchange vulnerabilities emerge, considering the latest version contains more features, such as calendaring functionality and RSS feeds.
"The more code and the more things that you have turned on that you're actively managing or trying to keep up with...the more configuration issues you have," he said.