November 10, 2020—KB4586781 (OS Builds 19041.630 and 19042.630)

Applies to: Windows 10, version 2004, all editionsWindows Server version 2004Windows 10, version 20H2, all editions

Highlights


  • Updates to improve security when using input devices such as a mouse, keyboard, or pen.
  • Updates to improve security when using Microsoft Office products.
  • Updates to improve security when Windows performs basic operations.
  • Updates the 2020 DST start date for the Fiji Islands to December 20, 2020.

Improvements and fixes


If you installed earlier updates, only the new fixes contained in this package will be downloaded and installed on your device.

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

Known issues in this update


Symptom Workaround
Users of the Microsoft Input Method Editor (IME) for Japanese or Chinese languages might experience issues when attempting various tasks. You might have issues with input, receive unexpected results, or might not be able to enter text. For more information about the issues, workaround steps, and the currently resolved issues, please see KB4564002

System and user certificates might be lost when updating a device from Windows 10, version 1809 or later to a later version of Windows 10. Devices will only be impacted if they have already installed any Latest cumulative update (LCU) released September 16, 2020 or later and then proceed to update to a later version of Windows 10 from media or an installation source which does not have an LCU released October 13, 2020 or later integrated. This primarily happens when managed devices are updated using outdated bundles or media through an update management tool such as Windows Server Update Services (WSUS) or Microsoft Endpoint Configuration Manager. This might also happen when using outdated physical media or ISO images that do not have the latest updates integrated.

Note Devices using Windows Update for Business or that connect directly to Windows Update are not impacted. Any device connecting to Windows Update should always receive the latest versions of the feature update, including the latest LCU, without any extra steps.

If you have already encountered this issue on your device, you can mitigate it within the uninstall window by going back to your previous version of Windows using the instructions here. The uninstall window might be 10 or 30 days depending on the configuration of your environment and the version you’re updating to. You will then need to update to the later version of Windows 10 after the issue is resolved in your environment. Note Within the uninstall window, you can increase the number of days you have to go back to your previous version of Windows 10 by using the DISM command /Set-OSUninstallWindow. You must make this change before the default uninstall window has lapsed. For more information, see DISM operating system uninstall command-line options.

We are working on a resolution and will provide updated bundles and refreshed media in the coming weeks.

After installing this update on domain controllers (DCs) and read-only domain controllers (RODCs) in your environment, you might encounter Kerberos authentication and ticket renewal issues. This is caused by an issue in how CVE-2020-17049 was addressed in these updates.

For specific symptoms and behaviors related to this issue, please see the Windows release health page for Windows Server, version 20H2 or Windows Server, version 2004 . 

Note This issue only affects Windows Servers, Windows 10 devices and applications in enterprise environments.

This issue is resolved in KB4594440.

How to get this update


Before installing this update

Microsoft strongly recommends you install the latest servicing stack update (SSU) for your operating system before installing the latest cumulative update (LCU). SSUs improve the reliability of the update process to mitigate potential issues while installing the LCU and applying Microsoft security fixes. For general information about SSUs, see Servicing stack updates and Servicing Stack Updates (SSU): Frequently Asked Questions.

If you are using Windows Update, the latest SSU (KB4586864) will be offered to you automatically. To get the standalone package for the latest SSU, search for it in the Microsoft Update Catalog.

Release Channel Available Next Step
Windows Update and Microsoft Update Yes None. This update will be downloaded and installed automatically from Windows Update.
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 10, version 1903 and later

Classification: Security Updates

 

File information

For a list of the files that are provided in this update, download the file information for cumulative update 4586781

Note Some files erroneously have “Not applicable” in the “File version” column of the CSV file. This might lead to false positives or false negatives when using some third-party scan detection tools to validate the build.