The software maker plugged 34 holes and designated most of them "critical," Microsoft's most severe rating. Among them are fixes for Windows Vista, Windows XP, Windows 2000 and even Windows 7, which doesn't go on sale to consumers until Oct. 22 but has been in use by early testers and software developers.
The patches target a wide array of Microsoft software, including the Internet Explorer Web browser, Media Player, Outlook and the Silverlight technology underlying multimedia Web sites.
Security researchers at McAfee Inc., which makes antivirus software, noted that many of the holes addressed Tuesday are dangerous because they expose regular PC users to harmful programming code when they visit rigged Web sites or play media files that have been tampered with.
Consumers can get the updates by turning on the "Automatic Updates" feature in Windows or by visiting www.microsoft.com/security.
Previously, the most security flaws Microsoft had addressed in a single update was 31, which happened in June.