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

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

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

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

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".
  • 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.

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

microsoft windows security-updates-download september 2021

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

Summary
Microsoft Windows Security Updates September 2021 overview
Article Name
Microsoft Windows Security Updates September 2021 overview
Description
Microsoft has released security updates and non-security updates for its Windows operating system on the Windows September 2021 Patch Day.
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Ghacks Technology News
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Comments

  1. Franck said on September 14, 2021 at 8:13 pm
    Reply

    Thank you for the great sum-up, as always!

  2. Paul(us) said on September 14, 2021 at 9:04 pm
    Reply

    Thanks Martin for guiding me thru this smooth update so I have now a Windows 10 pro., version 21H1, o.s. build 19043.1237

  3. chesscanoe said on September 14, 2021 at 10:32 pm
    Reply

    It seems strange Belarc Advisor says “KB5005699 9/14/2021 Security Update for Windows 10 (KB5005699)” was installed today, but a Google search gets me no hits. Maybe an SSU update for 21H1?

  4. Dave said on September 14, 2021 at 10:43 pm
    Reply

    Did they remedy the print spooler hack?

    1. Pingu The Clown said on September 15, 2021 at 4:51 pm
      Reply

      Of course not. What did you expect from a company that has no idea what they’re doing.. Here we go, once more: If you don’t want your computer infested with hardcoded adware, leaking all your info/data 24/7 and quite possible gets you yet another ransomware virus by just LOOKING at a document: use another operating system. Anything that is not from Microsoft.

      1. Capt Obvious said on September 20, 2021 at 3:57 pm
        Reply

        True.

  5. vdias said on September 15, 2021 at 9:40 am
    Reply

    Cannot find this one…

    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)

  6. RobG said on September 16, 2021 at 11:11 am
    Reply

    Useful info, Martin. Thanks.
    BTW. I like the new layout of the Ghacks website apart from the Popular Posts in the right hand column. I’ve often clicked on many of these ‘popular’ posts over the past few months’, only to realise that they are around 2 to 4 years old. Are these posts still relevant, or could that column be renamed ‘previous posts’ perhaps?

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