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Release Date:

10/13/2020

Version:

Security-only update

NEW
IMPORTANT Release notes are changing! To learn about the new URL, metadata updates, and more, see What’s next for Windows release notes.

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).

IMPORTANT Starting 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:

  • Corrects the end date for daylight savings time (DST) in 2021 for the Fiji Islands. For more information, see DST correction in Windows for the Fiji Islands: October 13, 2020.

  • Security updates to Windows App Platform and Frameworks, Windows Graphics, Windows Shell, Windows Silicon Platform, Windows Cloud Infrastructure, Windows Fundamentals, Windows Authentication, Windows Virtualization, Windows Kernel, Windows Core Networking, Windows Network Security and Containers, Windows Remote Desktop, and Windows SQL components.

For more information about the resolved security vulnerabilities, please refer to the Security Update Guide.

Known issues in this update

Symptom

Workaround

Certain operations, such as rename, that you perform on files or folders that are on a Cluster Shared Volume (CSV) may fail with the error, “STATUS_BAD_IMPERSONATION_LEVEL (0xC00000A5)”. This occurs when you perform the operation on a CSV owner node from a process that doesn’t have administrator privilege.

Do one of the following:

  • 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.

When installing a third-party driver, you might receive the error, “Windows can’t verify the publisher of this driver software”. You may also see the error “No signature was present in the subject” when attempting to view the signature properties using Windows Explorer.

This issue occurs when one or more of the following is present in a driver package:

  • An improperly formatted catalog file is identified during validation by Windows. Starting with this release, Windows will require the validity of DER encoded PKCS#7 content in catalog files. Catalogs files must be signed per section 11.6 of describing DER-encoding for SET OF members in X.690.

  • A driver catalog file extension is not one of supported extensions.

If this happens you should contact the driver vendor or device manufacturer (OEM) and ask them for an updated driver to correct the issue.

How to get this update

Before installing this update

We 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

REMINDER If you are using Security-only updates, you will also need to install all previous Security-only updates and the latest cumulative update for Internet Explorer (KB4577010).

 

Install this update

Release Channel

Available

Next Step

Windows Update and Microsoft Update

No

See the other options below.

Microsoft Update Catalog

Yes

To get the standalone package for this update, go to the Microsoft Update Catalog website.

Windows Server Update Services (WSUS)

Yes

This update will automatically sync with WSUS if you configure Products and Classifications as follows:

Product: Windows 8.1, Windows Server 2012 R2, Windows Embedded 8.1 Industry Enterprise, Windows Embedded 8.1 Industry Pro

Classification: Security Updates

 

File information

For a list of the files that are provided in this update, download the file information for update 4580358

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