January 12, 2021 - KB4598285 (Monthly Rollup)
Applies to: Windows 8.1, Windows Server 2012 R2, Windows Embedded 8.1 Industry Enterprise, Windows Embedded 8.1 Industry Pro
IMPORTANT Adobe Flash Player went out of support on December 31, 2020. For more information, see Adobe Flash end of support on December 31, 2020. Flash content will be blocked from running in Flash Player beginning January 12, 2021. For more information, see Adobe Flash Player EOL General Information Page.
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 KB4592484 (released December 8, 2020) and addresses the following issues:
For more information about the resolved security vulnerabilities, please refer to the new Security Update Guide website.
- Addresses a security bypass vulnerability that exists in the way the Printer Remote Procedure Call (RPC) binding handles authentication for the remote Winspool interface. For more information, see KB4599464.
- Addresses a security vulnerability issue with HTTPS-based intranet servers. After you install this update, HTTPS-based intranet servers cannot leverage a user proxy to detect updates by default. Scans that use these servers will fail if the clients do not have a configured system proxy.
If you must leverage a user proxy, you must configure the behavior by using the Windows Update policy Allow user proxy to be used as a fallback if detection using system proxy fails. To make sure that the highest levels of security, additionally leverage Windows Server Update Services (WSUS) Transport Layer Security (TLS) certificate pinning on all devices. For more information, see Changes to scans, improved security for Windows devices.
Note This change does not affect customers who use HTTP WSUS servers.
- Security updates to Windows App Platform and Frameworks, Windows Graphics, Windows Media, Windows Fundamentals, Windows Cryptography, and Windows Virtualization.
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:
Microsoft is working on a resolution and will provide an update in an upcoming release.
- Perform the operation from a process that has administrator privilege.
- Perform the operation from a node that doesn’t have CSV ownership.
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 (KB4566425) 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
For a list of the files that are provided in this update, download the file information for update 4598285.
Direct download links for KB4598285 MSU file from Microsoft Update Catalog:
Download KB4598285 MSU for Windows 8.1 32-bit (x86) - 348.0 MB
Download KB4598285 MSU for Windows 8.1 64-bit (x64) - 537.4 MB