Microsoft has released an urgent update to stop hackers taking control of computers with a single email. The unusual bug, in Microsoft anti-malware software such as Windows Defender, could be exploited without the recipient even opening the message. Hackers could exploit the flaw simply by sending an infected email, instant message or getting the user to click on a web browser link. Researchers working for Google’s Project Zero cyber-security unit discovered the flaw at the weekend.

The fix has been specially pushed out hours before the software giant’s monthly Tuesday security update.

Windows 8, 8.1, 10 and Windows Server operating systems were affected by the bug. Anti-virus software such as Windows Defender would simply have to scan the malicious content for the exploit to be triggered.

Cyber-security expert Graham Cluley said that Microsoft had acted brilliantly to release the patch so quickly. (9th May 2017)