October 13, 2020—KB4579311 (OS Build 19041.572)

Applies to: Windows 10, version 2004, all editionsWindows Server version 2004

Highlights


  • Updates to improve security when using Microsoft Office products.
  • Updates for verifying usernames and passwords.
  • Updates to improve security when Windows performs basic operations.

Improvements and fixes


This security update includes quality improvements. Key changes include:

  • Addresses an issue with a possible elevation of privilege in win32k. 
  • Addresses an issue with the Group Policy service that might recursively delete critical files in alphabetic order from %systemroot%\system32. This issue occurs when a policy has been configured to delete cached profiles. These file deletions might cause stop error “0x5A (CRITICAL_SERVICE_FAILED)” boot failures.
  • Addresses an issue with creating null ports using the user interface. 
  • Security updates to Windows App Platform and Frameworks, Microsoft Graphics Component, Windows Media, Windows Fundamentals, Windows Authentication, Windows Virtualization, and Windows Kernel.

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 Security Update Guide.

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
When installing a third-party driver, you might receive the error, “Windows can’t verify the publisher of this driver software”. You might 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 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.

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

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 (KB4577266) 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 4579311

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.