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The Update Bureau

Monthly Patch Briefing

September 2026

66 updates released this month across 8 product lines · 34 Patch Tuesday · 10 out-of-band · 2 previews · 2 exploited vulnerabilities fixed.

Release volume

66 updates released

21 more than August (45), vs 52/mo in 2026.

Sep 2026
66
Aug 2026
45
2026 average
52/mo

Security flaws fixed

851 vulnerabilities

+575 flaws compared to August (276).

Sep 2026
851
Aug 2026
276
2026 average
260/mo

Critical & urgent

78 critical · 2 zero-days

24 critical in August, plus 10 out-of-band releases this month .

Sep critical
78
Aug critical
24
2026 average
22/mo

2026 Year-to-Date Trend

2,337 security flaws fixed across 464 updates in 2026

199 critical flaws and 15 exploited zero-days patched across the 9 published months of 2026.

Distinct security flaws fixed per month Jan – Sep 2026
September 2026
Windows 11
Monthly security update
3 out-of-band 2 previews 650 fixed 56 critical 1 exploited 5 with issues
650 fixed · 56 critical Exploited CVE-2026-81963 (Windows Update Stack Elevation of Privilege Vulnerability)
Windows 10
Monthly security update
3 out-of-band 652 fixed 62 critical 1 exploited 4 with issues
652 fixed · 62 critical Exploited CVE-2026-85880 (Windows Advanced Local Procedure Call (ALPC) Elevation of Privilege Vulnerability)
Windows Server
Monthly security update
4 out-of-band 702 fixed 65 critical 2 exploited 6 with issues
702 fixed · 65 critical Exploited CVE-2026-81963 (Windows Update Stack Elevation of Privilege Vulnerability) · CVE-2026-85880 (Windows Advanced Local Procedure Call (ALPC) Elevation of Privilege Vulnerability)

Vulnerabilities fixed, by version

Product Version Monthly update & build Critical Important Total
Windows 11
Windows 11, version 26H2 · · 1 1
Windows 11
Windows 11, version 26H1 KB5124012 28000.2954 55 587 642
Windows 11
Windows 11, version 25H2 KB5124008 26200.9445 54 589 643
Windows 11
Windows 11, version 24H2 KB5124008 26100.9445 54 589 643
Windows 11
Windows 11, version 23H2 KB5122880 22631.7582 53 561 614
Windows 10
Windows 10 Enterprise LTSC 2019 KB5122876 17763.9245 55 567 622
Windows 10
Windows 10 Enterprise LTSB 2016 KB5123099 14393.9512 45 514 559
Windows 10
Windows 10, version 22H2 KB5122878 19045.7725 49 529 578
Windows 10
Windows 10 Enterprise LTSC 2021 KB5122878 19044.7725 49 529 578
Windows Server
Windows Server 2025 KB5122871 26100.33438 64 626 690
Windows Server
Windows Server 2022 KB5122882 20348.5622 61 590 651
Windows Server
Windows Server 2019 KB5122876 17763.9245 59 567 626
Windows Server
Windows Server 2016 KB5123099 14393.9512 49 514 563
.NET Framework
.NET Framework 4.8.1 KB5126052 4.8.9347.0 · 2 3
.NET Framework
.NET Framework 4.8 KB5126046 4.8.4806.0 · 2 3
.NET Framework
.NET Framework 4.7.2 KB5126043 4.7.4145.0 · 2 2
.NET Framework
.NET Framework 3.5 KB5126052 2.0.50727.9183 · 2 3
SQL Server
SQL Server 2025 KB5122769 17.0.4085.5 4 52 56
SQL Server
SQL Server 2022 KB5122768 16.0.4275.2 4 48 52
SQL Server
SQL Server 2019 KB5122772 15.0.4490.9 3 49 52
SQL Server
SQL Server 2017 KB5122774 14.0.3550.4 1 44 45
SharePoint Server
SharePoint Server Subscription Edition KB5002908 16.0.20326.20136 · 18 19
Office Online Server
Office Online Server KB5002910 16.0.10417.20207 · 5 28
Exchange Server
Exchange Server Subscription Edition KB5121608 15.2.2562.49 · 9 9
Exchange Server
Exchange Server 2019 KB5121609 15.2.1748.51 · 9 9
Exchange Server
Exchange Server 2016 KB5121611 15.1.2507.73 · 8 8

All updates

All updates:
  • Windows 11 · 26H1
    Windows 11 Windows 11 Insider 26H1 Insider Preview
    Experimental Channel
    Build 28120.3122

    Small changes to the overall experience on PCs

    Brings general improvements and fixes to PCs in the Experimental Channel.

  • Windows 11 · 26H1
    Windows 11 Windows 11 Insider 26H1 Insider Preview
    Beta Channel
    Build 28020.3112

    Plan9 folder access fixed in some virtual machine apps

    Beta Channel Insiders receive a gradual fix for Plan9 folder sharing in some applications that use HCS-managed virtual machines, plus a small set of general improvements.

    Changes 1 fix
  • Windows 11 · 26H2
    Windows 11 Windows 11 Insider 26H2 Insider Preview
    Experimental Channel
    Build 26340.9577

    More Start activity and broader Narrator math reading support

    Build 26340.9577 for the Experimental Channel gradually adds more phone activity in Start, expands Narrator math reading, and brings other changes and a USB audio fix.

    Changes 1 new · 5 improved · 1 fix
  • Windows 11 · 25H2
    Windows 11 Windows 11 Insider 25H2 Insider Preview
    Beta Channel
    Build 26220.9568

    Pointer Indicator and a lower-glare Magnifier theme

    Adds Pointer Indicator, previews of Phone Link activity in Start, and a Magnifier contrast theme. It also adds dark mode to File Explorer Folder Options and fixes an issue with some USB audio devices.

    Changes 4 new · 1 improved · 1 fix
  • Windows 11 · 24H2, 25H2, 26H2
    Windows 11 24H2 / 25H2 / 26H2 Windows 11 24H2 / 25H2 / 26H2 Optional preview
    Preview Final update for this version Final update for this version Updated
    KB5124010

    New touchpad gestures, emoji and Widgets; Remote Desktop issue remains

    Adds Windows features and fixes several problems, but non-admin Remote Desktop connections might still fail on managed devices with Administrator protection enabled. It is the final preview for version 24H2.

    Builds 26100.9550 26200.9550 26300.9550
    Replaced by KB5127648 →
  • Windows 11 · 26H1
    Windows 11 26H1 Windows 11 26H1 Optional preview
    Preview Updated
    KB5124006

    Remote Desktop failures reported; taskbar moves to four screen edges

    Adds taskbar and Start menu customization, while some non-admin Remote Desktop connections can fail on devices with Administrator protection enabled.

    Build 28000.3086
    Replaced by KB5127646 →
  • Windows 11 · Future platforms
    Windows 11 Windows 11 Insider Future platforms Insider Preview
    Experimental Channel
    Build 29671.1000

    Hyper-V folder sharing and UAC freeze fixes

    Fixes Linux VM folder sharing and freezes triggered by UAC prompts. The notes also list unresolved performance and VMware issues.

    Changes 2 fixes
  • Windows 11 · 26H1
    Windows 11 Windows 11 Insider 26H1 Insider Preview
    Experimental Channel
    Build 28120.3032

    Cloud rebuild and a fix for Linux shared folders

    Adds Cloud rebuild for reinstalling Windows from Recovery and fixes Plan9 folder sharing with Linux VMs. It also resolves an Easy Anti-Cheat launch issue.

    Changes 1 new · 2 fixes
  • Windows 11 · 26H2
    Windows 11 Windows 11 Insider 26H2 Insider Preview
    Experimental Channel
    Build 26340.9502

    Magnifier contrast themes and Cloud rebuild drive sanitizing

    Adds Magnifier contrast themes and new Cloud rebuild options, and fixes Plan9 folder sharing with Linux VMs and File History backups.

    Changes 5 new · 2 fixes
  • Windows 11 · 25H2
    Windows 11 Windows 11 Insider 25H2 Insider Preview
    Beta Channel
    Build 26220.9492

    Live Captions screen reader setting and File History backup fix

    Beta Channel Insiders get a new Live Captions setting for screen reader audio, plus fixes for Linux VM folder sharing and File History backups.

    Changes 1 improved · 2 fixes
  • SQL Server · CU9
    SQL Server 2025 CU9 SQL Server 2025 CU9 Cumulative update
    KB5122048

    Parallel session results can be wrong; recovery queries can crash

    CU9 for SQL Server 2025 includes 45 fixes, but it also has open issues that can affect parallel SESSION_CONTEXT queries, MSDASQL linked servers, and queries during database recovery.

    Build 17.0.5005.3
    Known issues 3 open
    Replaced by KB5126967 →
  • SQL Server · CU27
    SQL Server 2022 CU27 SQL Server 2022 CU27 Cumulative update
    KB5104824

    New multi-database link mode; recovery queries can trigger access violations

    Adds a multi-database link mode and includes 42 fixes. Open issues include incorrect SESSION_CONTEXT results in parallel plans and access violations during database recovery.

    Build 16.0.4295.3
    Known issues 4 open
    Replaced by KB5126934 →
  • Windows 11 · 24H2, 25H2, 26H2
    Windows 11 24H2 / 25H2 / 26H2 Windows 11 24H2 / 25H2 / 26H2 Out-of-band security update
    Out-of-band Updated
    KB5129195

    Remote Desktop failures and USB multichannel audio fixed

    Protects against a Windows User-Mode Power Service elevation-of-privilege flaw and addresses Remote Desktop instability and USB multichannel audio failures. Other USB Audio Class 1.0 problems remain.

    Builds 26100.9457 26200.9457 26300.9457
    Security 1 CVE
    Replaced by KB5124010 →
  • Windows 11 · 26H1
    Windows 11 26H1 Windows 11 26H1 Out-of-band security update
    Out-of-band Updated
    KB5129194

    Secure Kernel protections and fixes for Remote Desktop and USB audio

    Secure Kernel protections address a critical elevation-of-privilege flaw. The release also fixes Remote Desktop failures and some USB audio modes, while other USB audio problems remain.

    Build 28000.2956
    Security 2 CVEs 1 critical
    Replaced by KB5124006 →
  • Windows 11 · 23H2
    Windows 11 23H2 Windows 11 23H2 Out-of-band update
    Out-of-band
    KB5129242

    Remote Desktop failures and Linux shared-folder access fixed

    Addresses Remote Desktop instability, restores Plan9 host-folder access to Linux VMs, and resolves only 8-channel or 3D-mode symptoms for affected USB audio devices. Other USB audio symptoms remain.

    Build 22631.7584
    Replaced by KB5126653 →
  • Windows 10 · 21H2, 22H2
    Windows 10 21H2 / 22H2 Windows 10 21H2 / 22H2 Out-of-band update
    Out-of-band Updated
    KB5129236

    Remote Desktop instability and USB multichannel audio fixed

    Fixes Remote Desktop failures, Linux VM shared-folder access, and 8-channel or 3D USB audio problems. Other USB Audio Class 1.0 symptoms remain unresolved.

    Builds 19044.7727 19045.7727
    Replaced by KB5126657 →
  • Windows 10 · 1809
    Windows 10 1809 Windows 10 1809 Out-of-band update Also for Windows Server
    Out-of-band Updated
    KB5129238

    Remote Desktop failures and multichannel USB audio fixed

    Addresses Remote Desktop connection and sign-in failures and fixes 8-channel or 3D audio problems on some USB Audio Class 1.0 devices.

    Build 17763.9247
    Replaced by KB5126651 →
  • Windows 10 · 1607
    Windows 10 1607 Windows 10 1607 Out-of-band update Also for Windows Server
    Out-of-band
    KB5129239

    Remote Desktop instability and multichannel USB audio addressed

    Addresses Remote Desktop instability and fixes failures in 8-channel or 3D audio on some USB Audio Class 1.0 devices. Other USB audio symptoms remain unresolved.

    Build 14393.9514
    Replaced by KB5126868 →
  • Windows Server · 2025
    Windows Server 2025 Windows Server 2025 Out-of-band update
    Out-of-band Updated
    KB5129235

    Remote Desktop failures fixed; USB audio partly restored

    Remote Desktop connections and sign-ins work again in affected environments. USB audio in 8-channel or 3D modes is also fixed, but other USB audio problems remain.

    Build 26100.33451
    Known issues 1 open
    Replaced by KB5126646 →
  • Windows Server · 2022
    Windows Server 2022 Windows Server 2022 Out-of-band update
    Out-of-band
    KB5129237

    Remote Desktop failures and multichannel USB audio fixed

    Remote Desktop connection and sign-in failures are fixed, along with 8-channel and 3D audio problems on some USB Audio Class 1.0 devices. The update is available only through the Microsoft Update Catalog.

    Build 20348.5631
    Known issues 1 open
    Replaced by KB5126655 →
  • Windows Server · 2019
    Windows Server 2019 Windows Server 2019 Out-of-band update Also for Windows 10
    Out-of-band Updated
    KB5129238

    Remote Desktop instability addressed; 8-channel USB audio restored

    Addresses Remote Desktop instability and restores 8-channel or 3D audio on affected USB Audio Class 1.0 devices. Other USB audio symptoms might remain.

    Build 17763.9247
    Replaced by KB5126651 →
  • Windows Server · 2016
    Windows Server 2016 Windows Server 2016 Out-of-band update Also for Windows 10
    Out-of-band Updated
    KB5129239

    Remote Desktop failures and multichannel USB audio fixed

    Fixes Remote Desktop failures and USB audio problems in 8-channel and 3D modes. Other USB Audio Class 1.0 symptoms remain unresolved.

    Build 14393.9514
    Replaced by KB5126868 →
  • Windows 11 · Future platforms
    Windows 11 Windows 11 Insider Future platforms Insider Preview
    Experimental Channel
    Build 29667.1000

    Taskbar moves to new screen edges and can shrink

    Adds taskbar position and size options, Emoji 17.0, and fixes for upgrades, touchpad zoom, Remote Desktop, and Wi-Fi.

    Changes 3 new · 4 improved · 5 fixes
  • Windows 11 · 26H1
    Windows 11 Windows 11 Insider 26H1 Insider Preview
    Experimental Channel
    Build 28120.3002

    Bluetooth gamepad navigation and pinned apps in Windows Share

    Build 28120.3002 gradually adds gamepad navigation to Bluetooth quick settings and lets you pin favorite apps in Windows Share. Easy Anti-Cheat might fail to launch.

    Changes 2 new
  • Windows 11 · 26H1
    Windows 11 Windows 11 Insider 26H1 Insider Preview
    Beta Channel
    Build 28020.2991

    Bluetooth gamepad controls and pinned apps in Windows Share

    Beta Channel Insiders get gamepad navigation for Bluetooth quick settings, the option to pin favorite apps in Windows Share, and general improvements and fixes.

    Changes 2 new