Microsoft Corp issued patches on Tuesday to fix a bug in its Windows operating system that remained undiscovered for 19 years.

The bug, which is present in every version of Microsoft Windows from Windows 95 onward, allows an attacker to remotely take over and control a computer.

IBM Corp's cybersecurity research team discovered the bug in May, describing it as a "significant vulnerability" in the operating system.

"The buggy code is at least 19 years old and has been remotely exploitable for the past 18 years," IBM X-Force research team said in its blog on Tuesday.