Microsoft issued six "critical" security patches on Tuesday to fix flaws in its software products that the company warned could allow attackers to take control of a user's computer.

Microsoft issued the patches as part of its monthly security bulletin. There were no patches issued in the update for the newest version of Windows, called Vista.

Microsoft defines a flaw as "critical" when the vulnerability could allow a damaging Internet worm to replicate without the user doing anything to the machine.

The world's biggest software maker said the critical flaws affected versions of its Windows, Office, Works, Internet Explorer and Microsoft Malware Protection Engine products. It rated the other holes at its lower threat level of "important."

The latest patches can be downloaded at www.microsoft.com/security.