Microsoft released an emergency fix or update to address a critical bug affecting all supported version of the Windows OS on Monday. This latest bug is highly dangerous as it allows hackers unrestricted access to victims’ Windows computers.

Microsoft Releases Emergency Security Fix For Windows Bug

A dangerous bug, but fixed now

To protect the customers and as a precautionary step, Microsoft decided not to wait for “Patch Tuesday,” its scheduled monthly security update. The tech firm last released such an emergency patch in November of 2014.

In a post on Monday, Microsoft said the “critical” vulnerability, suggesting a high degree of threat, allows hackers to take “complete control of the affected system.” According to Microsoft, a hacker could attack by influencing a user to open or visit a specially crafted document or a compromised Web page as the susceptibility relates to OpenType, a common format for computer fonts jointly developed by Microsoft and Adobe.

“An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights,” the blog said.

Two of every three PCs running on Windows Vista, Windows 7, Windows 8 and 8.1 and Window RT are affected by this bug, the company noted. Microsoft said there is no proof the fault had been used to attack yet, but noted such an attack could be used “consistently.”

Crucial time for Microsoft

Earlier this month, computer security researchers detected the fault by going through a huge collection of emails that leaked after cyber hackers hacked the systems of Italian surveillance firm Hacking Team. FireEye’s Genwei Jiang and Mateusz Jurczyk, who are a part of Google’s Project Zero security squad, are credited by Microsoft for flagging the fault.

For Microsoft, this emergency fix comes at a crucial time, as its new Window 10 launch is just a week away. The tech firm is advertising its latest OS version as highly secure compared to previous versions. The new Windows version comes with technology such as Device Guard, a tool capable of handling the latest reported bug, and Windows Hello, a biometric security system, which allows a user to add face, iris or fingerprint recognition for extra security.

On Wednesday, July 29th, all the users of Windows 7 and Windows 8.1 will get an opportunity to upgrade to the Windows 10 for free.