Microsoft has rushed out a patch to the critical WMF flaw in Windows.

Millions of users across the world will today download and install patch number 06-001, causing them to have to restart computers but providing protection against the hole in Windows' image-rendering engine that could allow a hacker complete control of your computer.

Microsoft said it was reacting to "strong customer sentiment that the release should be made available as soon as possible" to patch the flaw. The company was also feeling heat from security experts who said the vendor's response was too slow. Many even advised users to download and install a third-party patch, such was the risk involved.

Originally, Microsoft had said it was testing a patch that would be available next week on 10 January in its regular monthly patch release. The software giant originally found out about the WMF exploit on 27 December. The WMF flaw has already been exploited by several different forms of malicious code, making the patch even more time-critical.

Earlier this week, a beta of Microsoft's patch was mistakenly released on a security website, prompting the company to ask users for a second time to wait until it put out an official patch.

Microsoft has been working hard on the problem, promising observers that its "development and testing teams have put forth a considerable effort to address this issue".

Those running Windows Server Update Services will receive the update automatically. The update is also supported by Microsoft Baseline Security Analyzer 2.0, Systems Management Server, and Software Update Services.

Consumers who use Automatic Updates will receive the update automatically. Users also can manually download the update from Microsoft Update or Windows Update.