September 8, 2020—KB4577071 (Security-only update)

IMPORTANT Windows 8.1 and Windows Server 2012 R2 have reached the end of mainstream support and are now in extended support. Starting in July 2020, there will no longer be optional, non-security releases (known as “C” releases) for this operating system. Operating systems in extended support have only cumulative monthly security updates (known as the “B” or Update Tuesday release).

IMPORTANTStarting in July 2020, all Windows Updates will disable the RemoteFX vGPU feature because of a security vulnerability. For more information about the vulnerability, seeCVE-2020-1036 and KB4570006. After you install this update, attempts to start virtual machines (VM) that have RemoteFX vGPU enabled will fail, and messages such as the following will appear:If you re-enable RemoteFX vGPU, a message similar to the following will appear:

• “The virtual machine cannot be started because all the RemoteFX-capable GPUs are disabled in Hyper-V Manager.”
• “The virtual machine cannot be started because the server has insufficient GPU resources.”
• "We no longer support the RemoteFX 3D video adapter. If you are still using this adapter, you may become vulnerable to security risk. Learn more (https://go.microsoft.com/fwlink/?linkid=2131976)”

Improvements and fixes

This security update includes quality improvements. Key changes include:

• Updates time zone information for Yukon, Canada. For more information, see DST changes in Windows for Yukon, Canada: September 8, 2020.
• Security updates to Windows Media, Windows Input and Composition, Windows App Platform and Frameworks, Windows Graphics, Windows Cloud Infrastructure, Windows Authentication, Windows Cryptography, Windows Fundamentals, Windows Kernel, Windows Hybrid Cloud Networking, Windows Peripherals, Windows Storage and Filesystems, Windows Network Security and Containers, Windows Update Stack, and Windows SQL components.
  For more information about the resolved security vulnerabilities, please refer to the Security Update Guide.

Known issues in this update

• Perform the operation from a process that has administrator privilege.
• Perform the operation from a node that doesn’t have CSV ownership.
  Microsoft is working on a resolution and will provide an update in an upcoming release.

How to get this update

Before installing this updateWe strongly recommend that you install the latest servicing stack update (SSU) for your operating system before you install the latest Rollup. SSUs improve the reliability of the update process to mitigate potential issues while installing the Rollup and applying Microsoft security fixes. For general information about SSUs, see Servicing stack updates and Servicing Stack Updates (SSU): Frequently Asked Questions.If you use Windows Update, the latest SSU (KB4566425) will be offered to you automatically. To get the standalone package for the latest SSU, search for it in the Microsoft Update Catalog.

REMINDERIf you use Security-only updates, you will also need to install all previous Security-only updates and the latest Cumulative Update for Internet Explorer 11.