July 6, 2021—KB5004951 (Security-only update) Out-of-band

Important: Windows 7 and Windows Server 2008 R2 have reached the end of mainstream support and are now in extended support. Starting in July 2020, there will no longer be optional, non-security releases (known as "C" releases) for this operating system. Operating systems in extended support have only cumulative monthly security updates (known as the "B" or Update Tuesday release). Verify that you have installed the required updates listed in the How to get this update section before installing this update. For information about the various types of Windows updates, such as critical, security, driver, service packs, and so on, please see the following article. To view other notes and messages, see the Windows 7 and Windows Server 2008 R2 update history home page.

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.

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

Known issues in this update

Symptom	Workaround
After installing this update or later updates, connections to SQL Server 2005 might fail. You might receive the following error: "Cannot connect to <Server name>, Additional information: A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: Named Pipes Provider, error: 40 - Could not open a connection to SQL Server) (.Net SqlClient Data Provider)"	This is expected behavior due to a security hardening change in this update. To resolve this issue, you will need to update to a supported version of SQL Server.
After installing this update and restarting your device, you might receive the error, “Failure to configure Windows updates. Reverting Changes. Do not turn off your computer,” and the update might show as Failed in Update History.	This is expected in the following circumstances: If you are installing this update on a device that is running an edition that is not supported for ESU. For a complete list of which editions are supported, see KB4497181. If you do not have an ESU MAK add-on key installed and activated. If you have purchased an ESU key and have encountered this issue, please verify you have applied all prerequisites and that your key is activated. For information on activation, please see this blog post. For information on the prerequisites, see the How to get this update section of this article.
Certain operations, such as rename, that you perform on files or folders that are on a Cluster Shared Volume (CSV) may fail with the error, "STATUS_BAD_IMPERSONATION_LEVEL (0xC00000A5)". This occurs when you perform the operation on a CSV owner node from a process that doesn’t have administrator privilege.	Do one of the following: Perform the operation from a process that has administrator privilege. Perform the operation from a node that doesn’t have CSV ownership. Microsoft is working on a resolution and will provide an update in an upcoming release.

How to get this update

Before installing this update

IMPORTANT Customers who have purchased the Extended Security Update (ESU) for on-premises versions of these operating systems must follow the procedures in KB4522133 to continue receiving security updates after extended support ends. Extended support ends as follows:

For Windows 7 Service Pack 1 and Windows Server 2008 R2 Service Pack 1, extended support ends on January 14, 2020.
For Windows Embedded Standard 7, extended support ends on October 13, 2020.

For more information about ESU and which editions are supported, see KB4497181.

Note For Windows Embedded Standard 7, Windows Management Instrumentation (WMI) must be enabled to get updates from Windows Update or Windows Server Update Services.

Prerequisite:

You must install the updates listed below and restart your device before installing the latest Rollup. Installing these updates improves the reliability of the update process and mitigates potential issues while installing the Rollup and applying Microsoft security fixes.

The March 12, 2019 servicing stack update (SSU) (KB4490628). To get the standalone package for this SSU, search for it in the Microsoft Update Catalog. This update is required to install updates that are only SHA-2 signed.
The latest SHA-2 update (KB4474419) released September 10, 2019. If you are using Windows Update, the latest SHA-2 update will be offered to you automatically. This update is required to install updates that are only SHA-2 signed. For more information on SHA-2 updates, see 2019 SHA-2 Code Signing Support requirement for Windows and WSUS.
For Windows Thin PC, you must have the August 11, 2020 SSU (KB4570673) or a later SSU installed to make sure you continue to get the extended security updates starting with the October 13, 2020 updates.
To get this security update, you must reinstall the "Extended Security Updates (ESU) Licensing Preparation Package" (KB4538483) or the "Update for the Extended Security Updates (ESU) Licensing Preparation Package" (KB4575903) even if you previously installed the ESU key. The ESU licensing preparation package will be offered to you from WSUS. To get the standalone package for ESU licensing preparation package, search for it in the Microsoft Update Catalog.

After installing the items above, Microsoft strongly recommends that you install the latest SSU (KB4592510). If you are using Windows Update, the latest SSU will be offered to you automatically if you are an ESU customer. To get the standalone package for the latest SSU, search for it in the Microsoft Update Catalog. For general information about SSUs, see Servicing stack updates and Servicing Stack Updates (SSU): Frequently Asked Questions.

REMINDER If you are using Security-only updates, you will also need to install all previous Security-only updates and the latest cumulative update for Internet Explorer (KB5003636).

Install this update

Release Channel	Available	Next Step
Windows Update and Microsoft Update	No	See the other options below.
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 7 Service Pack 1, Windows Server 2008 R2 Service Pack 1, Windows Embedded Standard 7 Service Pack 1, Windows Embedded POSReady 7, Windows Thin PC Classification: Security Updates

File information

For a list of the files that are provided in this update, download the file information for update 5004951.

July 6, 2021—KB5004951 (Security-only update) Out-of-band

Improvements and fixes

Known issues in this update

How to get this update

File information

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