Microsoft is planning to release a single patch for its Windows operating system on this month's 'patch Tuesday'.

The vulnerability is rated 'critical' and the patch requires a system restart, the company said in an online security bulletin. 

'Critical' is Microsoft's highest severity ranking, indicating that the vulnerability can be exploited without any user interaction. The company has not provided any additional information about the forthcoming patch.

Microsoft releases patches on the second Tuesday of every month, allowing system administrators to plan and prepare for the release.

The release traditionally coincides with an update of Microsoft's Malicious Software Removal Tool and is followed by a webcast. This month's is on Wednesday 9 November at 11am US Pacific Time (7pm BST). 

The vendor urges computer users to apply the patch as soon as possible. As illustrated in August, worm authors sometimes need only a few days to develop malware that exploits newly published vulnerabilities.