July 6, 2021—KB5004950 (OS Build 10240.18969) Out-of-band

Release Date:

7/6/2021

Version:

OS Build 10240.18969

^12/8/20
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 1507 update history home page.

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

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.

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

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

Microsoft is not currently aware of any issues with this update.

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 (KB5001399) 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.
Windows Update for Business	Yes	None. This update will be downloaded and installed automatically from Windows Update in accordance with configured policies.
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 Classification: Security Updates