Microsoft has released an emergency patch to fix a vulnerability that could allow a bad actor to remotely access and control your computer. Tavis Ormandy, someone who researches vulnerabilities in software for a living, called it “the worst Windows remote code exec (execution flaw) in recent memory. This serious virus can do harm to “any devices running Windows XP through Windows 10,” said Ormandy.

There is no indication that hackers found the flaw before researchers  did, and it is very unlikely the flaw has been used against anyone.

If you are reading this on a Windows computer, the update has already been downloaded. Some computers will need a restart for the update to take place. Windows may have restarted during the night for you, if you did not shut down the computer yourself. If you have seen a system message asking you to restart to apply an update today, do so now. To check if you need to restart manually, click Start>Power. If the options are Shut down and Restart, you are in the clear. If the options are Update and Shut down and Update and Restart, we suggest you Update and Restart now.