July 6, 2021—KB5004945 (OS Builds 19041.1083, 19042.1083, and 19043.1083) Out-of-band

EXPIRATION NOTICE****IMPORTAN T As of 9/12/2023, this KB is only available from Windows Update. It is no longer available from the Microsoft Update Catalog or other release channels. We recommend that you update your devices to the latest security quality update.

**6/21/21
IMPORTANT **This release includes the Flash Removal Package. Taking this update will remove Adobe Flash from the machine. For more information, see the Update on Adobe Flash Player End of Support.

11/17/20 For information about Windows update terminology, see the article about the types of Windows updates and the monthly quality update types. To view other notes and messages, see the Windows 10, version 2004 update history home page. Note Follow @WindowsUpdate to find out when new content is published to the release information dashboard.

Highlights

• Updates a remote code execution exploit in the Windows Print Spooler service, known as “PrintNightmare”, as documented in CVE-2021-34527.

Improvements and fixes

Note: To view the list of addressed issues, click or tap the OS name to expand the collapsible section.

__

Windows 10 servicing stack update - 19041.1081, 19042.1081, and 19043.1081

• This update makes quality improvements to the servicing stack, which is the component that installs Windows updates. Servicing stack updates (SSU) ensure that you have a robust and reliable servicing stack so that your devices can receive and install Microsoft updates.

__

Windows 10, version 21H1

This security update includes quality improvements. Key changes include:

• This build includes all the improvements from Windows 10, version 2004.
• No additional issues were documented for this release.

__

Windows 10, version 20H2

This security update includes quality improvements. Key changes include:

• This build includes all the improvements from Windows 10, version 2004.
• No additional issues were documented for this release.

__

Windows 10, version 2004

This security update includes quality improvements. Key changes include:

• Addresses a remote code execution exploit in the Windows Print Spooler service, known as “PrintNightmare”, as documented in CVE-2021-34527. After installing this and later Windows updates, users who are not administrators can only install signed print drivers to a print server. By default, administrators can install signed and unsigned printer drivers to a print server. The installed root certificates in the system’s Trusted Root Certification Authorities trusts signed drivers. Microsoft recommends that you immediately install this update on all supported Windows client and server operating system, starting with devices that currently host the print server role. You also have the option to configure the RestrictDriverInstallationToAdministrators registry setting to prevent non-administrators from installing signed printer drivers on a print server. For more information, see KB5005010.

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

Windows Update Improvements

Microsoft has released an update directly to the Windows Update client to improve reliability. Any device running Windows 10 configured to receive updates automatically from Windows Update, including Enterprise and Pro editions, will be offered the latest Windows 10 feature update based on device compatibility and Windows Update for Business deferral policy. This doesn’t apply to long-term servicing editions.

Known issues in this update

__

Click or tap to view the known issues

Symptoms	Workaround
When using the Microsoft Japanese Input Method Editor (IME) to enter Kanji characters in an app that automatically allows the input of Furigana characters, you might not get the correct Furigana characters. You might need to enter the Furigana characters manually.Note The affected apps are using theImmGetCompositionString() function.	This issue is resolved in KB5005101.
Devices with Windows installations created from custom offline media or custom ISO image might have Microsoft Edge Legacy removed by this update, but not automatically replaced by the new Microsoft Edge. This issue is only encountered when custom offline media or ISO images are created by slipstreaming this update into the image without having first installed the standalone servicing stack update (SSU) released March 29, 2021 or later.Note Devices that connect directly to Windows Update to receive updates are not affected. This includes devices using Windows Update for Business. Any device connecting to Windows Update should always receive the latest versions of the SSU and latest cumulative update (LCU) without any extra steps.	To avoid this issue, be sure to first slipstream the SSU released March 29, 2021 or later into the custom offline media or ISO image before slipstreaming the LCU. To do this with the combined SSU and LCU packages now used for Windows 10, version 20H2 and Windows 10, version 2004, you will need to extract the SSU from the combined package. Use the following steps to extract the SSU:

1. Extract the cab from the msu via this command line (using the package for KB5000842 as an example): expand Windows10.0-KB5000842-x64.msu /f:Windows10.0-KB5000842-x64.cab <destination path> 2. Extract the SSU from the previously extracted cab via this command line:expand Windows10.0-KB5000842-x64.cab /f: <destination path>* 3. You will then have the SSU cab, in this example namedSSU-19041.903-x64.cab. Slipstream this file into your offline image first, then the LCU.

If you have already encountered this issue by installing the OS using affected custom media, you can mitigate it by directly installing the new Microsoft Edge. If you need to broadly deploy the new Microsoft Edge for business, see Download and deploy Microsoft Edge for business.
After installing this update, you might have issues printing to certain printers. Various brands and models are affected, primarily receipt or label printers that connect via USB.Note This issue is not related to CVE-2021-34527 or CVE-2021-1675.| This issue is resolved in KB5004237.
After installing the May 25, 2021 (KB5003214) and June 21, 2021 (KB5003690) updates, some devices cannot install new updates, such as the July 6, 2021 (KB5004945) or later updates. You will receive the error message, “PSFX_E_MATCHING_BINARY_MISSING”.| For more information and a workaround, see KB5005322.
Universal Windows Platform (UWP) apps might not open on devices that have undergone a Windows device reset. This includes operations that were initiated using Mobile Device Management (MDM), such as Reset this PC, Push-button reset, and Autopilot Reset. UWP apps you downloaded from the Microsoft Store are not affected. Only a limited set of apps are affected, including:

• App packages with framework dependencies
• Apps that are provisioned for the device, not per user account.

The affected apps will fail to open without error messages or other observable symptoms. They must be re-installed to restore functionality.| This issue is addressed in KB5015878 for all releases starting June 21, 2021 and later.

How to get this update

Before installing this update Microsoft now combines the latest servicing stack update (SSU) for your operating system with the latest cumulative update (LCU). For general information about SSUs, see Servicing stack updates and Servicing Stack Updates (SSU): Frequently Asked Questions.Prerequisite:For Windows Server Update Services (WSUS) deployment:

• Install the May 11, 2021 update (KB5003173) before you install the latest cumulative update.

For offline Deployment Image Servicing and Management (DISM.exe) deployment:

• If an image does not have the February 24, 2021 (KB4601382) or later cumulative update, install the January 12, 2021 SSU (KB4598481) and the May 11, 2021 update (KB5003173).

Install this update****Release Channel	Available	Next Step
Windows Update or Microsoft Update	Yes	None. This update will be downloaded and installed automatically from Windows Update.
Windows Update for Business	No	No longer available.
Microsoft Update Catalog	No	No longer available.
Windows Server Update Services (WSUS)	No	No longer available.

If you want to remove the LCU To remove the LCU after installing the combined SSU and LCU package, use the DISM/Remove-Package command line option with the LCU package name as the argument. You can find the package name by using this command:DISM /online /get-packages.Running Windows Update Standalone Installer (wusa.exe) with the**/uninstall** switch on the combined package will not work because the combined package contains the SSU. You cannot remove the SSU from the system after installation.

File information For a list of the files that are provided in this update, download the file information for cumulative update 5004945. For a list of the files that are provided in the servicing stack update, download the file information for the SSU - version 19041.1081, 19042.1081, and 19043.1081.