A least one of the alerts is deemed "critical," Microsoft's highest risk rating, the company said in a notice posted on its Web site on Thursday.
The notice did not specify which components of Windows are affected. Earlier this week, security company eEye Digital Security said it had found serious flaws in Windows 2000 and Internet Explorer. Microsoft is investigating the issues, a company representative has said.
In addition to the patches, the software giant will issue on Tuesday a "high-priority" update for Windows that is unrelated to security. That day is also tagged for the usual release of an updated version of the Windows Malicious Software Removal Tool, which detects and removes malicious code placed on computers, Microsoft said.
The company gave no further information on Thursday's bulletins, other than stating that the Windows fixes will require restarting the computer.
The Redmond, Wash., software giant provides information in advance of its monthly patch release day, which is every second Tuesday of the month, so people can prepare to install the patches. In July, Microsoft released three security bulletins, two for Windows and one for Office. All were rated critical.
Microsoft rates as critical any security issue that could allow a malicious Internet worm to spread without any action required on the part of the user.
Microsoft has set a time of Wednesday at 11 a.m. PDT to host a Webcast about the new fixes.
