Microsoft plans to release 12 security bulletins next Tuesday to patch bugs in several applications, including Windows, Office, and Visual Studio.

In a notice posted on its Web site Thursday, Microsoft announced it would post five updates for Windows; two for Office; one that affects both Windows and Visual Studio; one that affects Windows and Office; one for Step-by-Step Interactive Training; one for Data Access Components; and one that affects Windows Live OneCare, Antigen, Windows Defender, and ForeFront.

At least four of the updates are being called critical, which is Microsoft's highest warning.

The Internet Storm Center, a cooperative cyberthreat monitoring and alert system, keeps a list of Microsoft bugs that need to be patched. Right now, they show 14 known outstanding bugs, according to Johannes Ullrich, chief research officer at the SANS Institute and chief technology officer for the Internet Storm Center. Some of the bugs have been around, and unpatched, for several months now.

"It'll be great if [Microsoft] fixes the right ones," says Ullrich, who notes that next week's release will be one of the company's larger security updates. "Last month, they didn't fix any outstanding Office bugs, and they're high-value targets. It's important to get them fixed."

The updates will be available for manual download from the Microsoft Web site Tuesday. As usual, automatic updates to users' computers will begin shortly after that.