Microsoft is about to issue an emergency security update to plug a vulnerability which could allow an internet worm to be spread via a computer without the user doing anything.
The update is rated as critical for users of Windows 2000, XP and Server 2003 and the less severe rating of "important" for users of Windows Server 2008 and Windows Vista. The patch is scheduled for 10.00am Pacific Time (6pm BST).
There will be a webcast at 1.00pm Pacific Time (9pm BST) explaining the issue in more detail.
The exploit potentially allows remote code to be executed.
The Advance Notification is here.
Microsoft tries to make life easier for administrators by bundling its updates into one monthly slot, known as Patch Tuesday, in the second week of every month. It has broken this cycle before, but it is unusual. ®