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Important: This release includes the Flash Removal Package. Taking this update will remove Adobe Flash from the device. For more information, see the Update on Adobe Flash Player End of Support.

Important: Windows 8.1 and Windows Server 2012 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).

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 8.1 and Windows Server 2012 R2 update history home page.

Improvements and fixes

This security update includes improvements and fixes that were a part of update KB5003671 (released June 8, 2021) and addresses the following issues:

  • 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

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

We strongly recommend that you install the latest servicing stack update (SSU) for your operating system before you install the latest Rollup. SSUs improve the reliability of the update process to mitigate potential issues while installing the Rollup and applying Microsoft security fixes. For general information about SSUs, see Servicing stack updates and Servicing Stack Updates (SSU): Frequently Asked Questions.

If you use Windows Update, the latest SSU (KB5001403) 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 8.1, Windows Server 2012 R2, Windows Embedded 8.1 Industry Enterprise, Windows Embedded 8.1 Industry Pro

Classification: Security Updates

File information

For a list of the files that are provided in this update, download the file information for update 5004954

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