The National Security Agency is asking PC users to update their Windows operating system. A bug detected in the older versions of the Windows OS is reportedly very bad. Microsoft also urges users to download an update that contains a fix to the vulnerability.

The vulnerability is so bad that it may likely cause malware similar to one of the worst ones in history. It is the “WannaCry” ransomware from 2017.

According to the NSA, this new bug called “BlueKeep” could spread across the internet without users even interacting with it. It reportedly affects the Windows 7, Server 2003, Windows XP and Server 2008.

This BlueKeep is so dangerous that it triggered Microsoft to suggest an immediate update. Microsoft has now issued an update fix for Windows XP. Microsoft had actually stopped supporting this operating system since 2014.

About a million computers are currently still vulnerable to this BlueKeep malware. This forced Microsoft to issue a warning to users to update their Windows.

America’s NSA also issued a statement saying:

“This is the type of vulnerability that malicious cyber actors frequently exploit through the use of software code that specifically targets the vulnerability. For example, the vulnerability could be exploited to conduct denial of service attacks. It is likely only a matter of time before a remote exploitation code is widely available for this vulnerability. NSA is concerned that malicious cyber actors will use the vulnerability in ransomware and exploit kits containing other known exploits, increasing capabilities against other unpatched systems.”

The attack from this malware can apparently shut down computers and networks. It can also take complete control of a company’s system infrastructure.

Microsoft advises companies and personal users to update their Windows OS as soon as possible to prevent the bug from affecting their computers.