Microsoft Windows Security Updates September 2021 overview

Today is Patch Day over at Microsoft and the company has released security updates and non-security updates for Windows and other company products. Security updates have been released for all client and server versions of the Windows operating system that Microsoft supports. Other company products, such as Microsoft Office, have received updates as well.

Our Windows security updates overview for September 2021 provides system administrators, IT workers, and home users with information about the released updates.

You find the list of critical updates for each supported Windows operating system as well as the distribution of updates for each at the top. What follows are information about the released patches, links to support pages, information about known issues, and download details.

Click here to open the August 2021 Windows Patch Day overview here.

The Microsoft Windows Security Updates: September 2021

Click here to download an Excel spreadsheet that lists all released security updates: Microsoft-windows-security-updates-list-september-2021

Executive Summary

• Microsoft released security updates for all Windows client and server products.
• Security updates were released for other company products such as Azure Sphere, Microsoft Edge, Microsoft Office, Visual Studio, Dynamics Business Central Control or Microsoft Accessibility Insights for Android.
• The following client versions of Windows have known issues: Windows 7, Windows 8.1, Windows 10 version 1809, Windows 10 version 2004, 20H2, and 21H1
• The following server versions of Windows have known issues: Windows Server 2008, Windows Server 2008 R2, Windows Server 2012, Windows Server 2012 R2, Windows Server version 2004 and 20H2

Operating System Distribution

• Windows 7 (extended support only): 22 vulnerabilities: 2 critical and 20 important
  • Windows Scripting Engine Memory Corruption Vulnerability -- CVE-2021-26435
  • Windows WLAN AutoConfig Service Remote Code Execution Vulnerability -- CVE-2021-36965
• Windows 8.1: 24 vulnerabilities: 2 critical and 22 important
  • same as Windows 7
• Windows 10 version 1903 and 1909: 32 vulnerabilities: 2 critical and 30 important
  • same as Windows 7
• Windows 10 version 2004, 20H2 and 21H1 : 32 vulnerabilities, 2 critical and 30 important
  • same as Windows 7

Windows Server products

• Windows Server 2008 R2 (extended support only): 22 vulnerabilities: 2 critical and 20 important
  • Windows Scripting Engine Memory Corruption Vulnerability -- CVE-2021-26435
  • Windows WLAN AutoConfig Service Remote Code Execution Vulnerability -- CVE-2021-36965
• Windows Server 2012 R2: 24 vulnerabilities: 2 critical and 22 important
  • same as Windows Server 2008 R2.
• Windows Server 2016: 28 vulnerabilities: 2 critical and 26 important
  • same as Windows Server 2008 R2.
• Windows Server 2019: 32 vulnerabilities: 2 critical and 30 important
  • same as Windows Server 2008 R2.
• Windows Server 2022:  29 vulnerabilities: 7 critical and 18 important
  • same as Windows Server 2008 R2.

Windows Security Updates

Windows 7 SP1 and Windows Server 2008 R2

• Monthly Rollup: KB5005633
• Security-Only: KB5005615

Updates and improvements:

• Addresses an issue in which a driver might not install if the driver is signed with more than one code sign signatures.
• This update also contains miscellaneous security improvements to internal OS functionality.

Windows 8.1 and Windows Server 2012 R2

• Monthly Rollup: KB5005613
• Security-only: KB5005627

Updates and improvements:

• This update contains miscellaneous security improvements to internal OS functionality. No additional issues were documented for this release.

Windows 10 version 1909

• Support Page: KB5005566 

Updates and improvements:

• Addresses an issue that causes PowerShell to create an infinite number of child directories. This issue occurs when you use the PowerShell Move-Item command to move a directory to one of its children. As a result, the volume fills up and the system stops responding.
• Security updates

Windows 10 version 2004, 20H2 and 21H1

• Support Page: KB5005565 

Updates and improvements:

• Addresses an issue that causes PowerShell to create an infinite number of child directories. This issue occurs when you use the PowerShell Move-Item command to move a directory to one of its children. As a result, the volume fills up and the system stops responding.
• Security updates

Other security updates

2021-09 Cumulative Security Update for Internet Explorer (KB5005563)

Windows Server

2021-09 Security Monthly Quality Rollup for Windows Server 2008 (KB5005606)

2021-09 Security Only Quality Update for Windows Server 2008 (KB5005618)

2021-09 Security Only Quality Update for Windows Embedded 8 Standard and Windows Server 2012 (KB5005607)

2021-09 Security Monthly Quality Rollup for Windows Embedded 8 Standard and Windows Server 2012 (KB5005623)

2021-09 Cumulative Update for Microsoft server operating system version 21H2 for x64-based Systems (KB5005575)

2021-09 Cumulative Update for Windows Server 2016 and Windows 10 Version 1607 (KB5005573)

Servicing Stack Updates

2021-09 Servicing Stack Update for Windows Server 2016 and Windows 10 Version 1607 (KB5005698)

Known Issues

Windows 7 SP1 and Windows Server 2008 R2

• Certain operations may fail on Cluster Shared Volumes with the error "STATUS_BAD_IMPERSONATION_LEVEL (0xC00000A5)"
  • Workaround: run the operations from an elevated process, or from a node that does not have CSV ownership
• Updates may be reverted if the system does not support ESU.
  • Expected behavior.

Windows 8.1 and Windows Server 2012 R2

• Certain operations may fail on Cluster Shared Volumes with the error "STATUS_BAD_IMPERSONATION_LEVEL (0xC00000A5)"
  • Workaround: run the operations from an elevated process, or from a node that does not have CSV ownership

Windows 10 version 1809

• Some devices with unspecified Asian language packs installed may throw the error "0x800f0982 - PSFX_E_MATCHING_COMPONENT_NOT_FOUND".
  • Try uninstalling and reinstalling the recently added language packs, then running a manual check for updates.
  • If that does not work, Microsoft suggests to use the Reset this PC function and selecting to keep the files.

 

Windows 10 version 2004, 20H2 and 21H1

• Some devices may be unable to install updates, throwing the error "PSFX_E_MATCHING_BINARY_MISSING".
  • Check out our guide on fixing the error.
• Custom offline media or custom ISO image installations on devices may remove Microsoft Edge Legacy but may not replace it with the Chromium-based Microsoft Edge.
  • Workaround described on the support page.

Security advisories and updates

ADV 990001 -- Latest Servicing Stack Updates

Non-security updates

• 2021-09 Cumulative Update for .NET Framework 3.5 and 4.8 for Windows Server, version 20H2, Windows 10 Version 20H2, Windows Server, version 2004, Windows 10 Version 2004, Windows Server, version 1909, Windows 10 Version 1909, Windows Server 2019 (1903), and Windows 10 Version 1903 (KB5005548)

Microsoft Office Updates

You find Office update information here.

How to download and install the September 2021 security updates

Security updates are downloaded and installed automatically via Windows Update on most Home and some business/Enterprise systems.

Windows checks for updates frequently and will download those classified as security updates automatically to install them.

Windows administrators may check for the updates manually to download and install the patches right away.

1. Select Start, type Windows Update and load the Windows Update item that is displayed.
2. Select check for updates to run a manual check for updates.

Direct update downloads

Below are resource pages with direct download links, if you prefer to download the updates to install them manually.

Windows 7 and Server 2008 R2

• KB5005633 -- 2021-09 Security Monthly Quality Rollup for Windows 7
• KB5005615 -- 2021-09 Security Only Quality Update for Windows 7

Windows 8.1 and Windows Server 2012 R2

• KB5005613 -- 2021-09 Security Monthly Quality Rollup for Windows 8.1
• KB5005627 -- 2021-09 Security Only Quality Update for Windows 8.1

Windows 10 (version 1909)

• KB5005566 -- 2021-09 Cumulative Update for Windows 10 Version 1909

Windows 10 (version 2004)

• KB5005565 -- 2021-09 Cumulative Update for Windows 10 Version 2004

Windows 10 (version 20H2)

• KB5005565 -- 2021-09 Cumulative Update for Windows 10 Version 20H2

Windows 10 (version 21H1)

• KB5005565 -- 2021-09 Cumulative Update for Windows 10 Version 21H1

Additional resources

• September 2021 Security Updates release notes
• List of software updates for Microsoft products
• List of the latest Windows Updates and Services Packs
• Security Updates Guide
• Microsoft Update Catalog site
• Our in-depth Windows update guide
• How to install optional updates on Windows 10
• Windows 10 Update History
• Windows 8.1 Update History
• Windows 7 Update History

Advertisement