KB4577671 – Windows 10 1903 & 1909 Security update

On the patch Tuesday of Nov, Windows 10 receives a new cumulative update KB4577671 for devices running Windows 10 version 1903 and 1909. This patch improves the security update while using Microsoft Office products and Windows performs basic operations. The update increases the version number of 1909 to build 18363.1139 and of 1903 to build 18362.1139.

Like every Windows Update, you can download and install this patch update through the Windows Settings. Go to the Windows Updates and then click the Check for updates button to install the update. Now let’s explore the key changes in detail –

Windows 10 1903 & 1909 Security update

KB4577671 Changelog for 19H1 and 19H2

Here are the key changes –

KB4577671 – Windows 10 1903 & 1909 Security update

Windows 10, 1909

The key changes of this security update are –

  • With this security patch, Microsoft has included all the improvements from Windows 10, v1903.
  • And there is no other issue that has been recorded for this release.

Windows 10, 1903

The key changes of this security update are –

  • Microsoft team has worked on the possible elevation of privilege in win32k.
  • Next, the company has tried to resolve a problem related to the Group Policy service. It might recursively erase the critical files in alphabetic order from the %systemroot%\systm32 folder.
  • Another issue that has been addressed is associated with creating null ports using the user interface.
  • After installing this update, the application will not stop working when you use Visual Basic for Applications (VBA).

Known issues in this update

Apart from the changelog, there are three issues that have been found with this update. These are the following:

Issue: 1

You may receive a compatibility report when you try to update your Windows computer to v1903 or v1909.

During this, an error message will prompt on the screen saying, “Continuing with the installation of Windows will remove some optional features. You may need to add them back in Settings after the installation completes.” 

This issue commonly occurs when the local system accounts get blocked in a firewall from accessing the internet connection through HTTP.


You can reduce this issue if your computer has access to HTTP blocked for Local System accounts. 

To do this, turn on HTTP access for the Windows 10 Setup Dynamic Update utilizing the LOCAL SYSTEM account. 

Once you allow access, restart the installation of the update and the problem will be fixed.

Issue 2: 

You may encounter an error message while installing a third-party driver.

Here the errors are following, “Windows can’t verify the publisher of this driver software”.

Also, while trying to view the signature properties, you may see the following error message:

“No signature was present in the subject”.


This problem generally occurs when you detect an improperly formatted catalog file during validation by Windows.

Starting with this release, there is a need for the validity of DER-encoded PKCS#7 content in catalog files. Whereas the Catalogs files must be signed per section 11.6 of describing DER-encoding for SET OF members in X.690.

In that case, contact the driver vendor or device manufacturer (OEM). And then ask them for an updated driver to fix the issue.

How to download and install KB4577671 on Windows 10 19H2 & 19H1

Before you proceed, make sure you have installed the latest SSU KB4577670. You can use three methods to get the patch update on your Windows 10 device. Here are the followings:

1] Through Windows update

To download the update through Windows update, use the steps –

  • Right-click on Start and select Settings.
  • Then select Update & Security > Windows Updates.
  • On the right side, click the Check for updates button.
  • Wait for a while until it starts scanning and downloading the update.
  • Once it downloads KB4577671, click on the Install now button to install it.

2] Through Microsoft update catalog

You can also get the update through the Microsoft update catalog. Here are the steps:

  • Navigate to the Microsoft Update Catalog page. 
  • Download and run the standalone package that came along with this release.
  • Then double click on .MSU File to install the update.

3] Windows Server Update Services (WSUS)

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

  • Product: Windows 10 version 1903 and 1909.
  • Classification: Security Updates

Release Note: Update Catalog