October 13, 2020—KB4577671 (OS Builds 18362.1139 and 18363.1139)

Applies to: Windows 10, version 1903, all editionsWindows Server version 1903Windows 10, version 1909, all editions

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.
  • Updates for storing and managing files.

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 Security Update Guide.

Known issues in this update


Symptom Workaround
When updating to Windows 10, version 1903 or Windows 10, version 1909 from any previous version of Windows 10, you might receive a compatibility report dialog with "What needs your attention" at the top and the error, "Continuing with the installation of Windows will remove some optional features. You may need to add them back in Settings after the installation completes." You might receive this compatibility warning when LOCAL SYSTEM accounts are blocked in a firewall from accessing the internet via HTTP. This is caused by the Windows 10 Setup Dynamic Update (DU) being unable to download required packages.

This issue is resolved in KB4579919.

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 (KB4577670) will be offered to you automatically. To get the standalone package for the latest SSU, search for it in the Microsoft Update Catalog.

Install this update

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 4577671

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.