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The Update Bureau

Monthly Patch Briefing

January 2026

41 updates released this month across 7 product lines · 16 Patch Tuesday · 14 out-of-band · 3 previews · 1 exploited vulnerability fixed.

Release volume

41 updates released

14 more than December (27), vs 41/mo in 2026.

Jan 2026
41
Dec 2025
27
2026 average
41/mo

Security flaws fixed

109 vulnerabilities

+60 flaws compared to December (49).

Jan 2026
109
Dec 2025
49
2026 average
109/mo

Critical & urgent

5 critical · 1 zero-day

0 critical in December, plus 14 out-of-band releases this month .

Jan critical
5
Dec critical
0
2026 average
5/mo
January 2026
Windows 11
Monthly security update
4 out-of-band 1 preview 90 fixed 3 critical 1 exploited 6 with issues
90 fixed · 3 critical Exploited CVE-2026-20805 (Desktop Window Manager Information Disclosure Vulnerability)
Windows 10
Monthly security update
4 out-of-band 73 fixed 1 critical 1 exploited 4 with issues
73 fixed · 1 critical Exploited CVE-2026-20805 (Desktop Window Manager Information Disclosure Vulnerability)
Windows Server
Monthly security update
6 out-of-band 90 fixed 3 critical 1 exploited 8 with issues
90 fixed · 3 critical Exploited CVE-2026-20805 (Desktop Window Manager Information Disclosure Vulnerability)
.NET Framework
Monthly security update
2 previews 0 fixed
  • No Patch Tuesday security update this month —
0 fixed · 0 critical

Vulnerabilities fixed, by version

Product Version Monthly update & build Critical Important Total
Windows 11
Windows 11, version 25H2 KB5074109 26200.7623 3 82 87
Windows 11
Windows 11, version 24H2 KB5074109 26100.7623 3 82 87
Windows 11
Windows 11, version 23H2 KB5073455 22631.6491 2 77 80
Windows 10
Windows 10 Enterprise LTSC 2019 KB5073723 17763.8276 1 68 70
Windows 10
Windows 10 Enterprise LTSB 2016 KB5073722 14393.8783 1 49 51
Windows 10
Windows 10, version 22H2 KB5073724 19045.6809 1 71 73
Windows 10
Windows 10 Enterprise LTSC 2021 KB5073724 19044.6809 1 71 73
Windows Server
Windows Server 2025 KB5073379 26100.32230 3 82 86
Windows Server
Windows Server 2022 KB5073457 20348.4648 1 76 78
Windows Server
Windows Server 2019 KB5073723 17763.8276 1 70 72
Windows Server
Windows Server 2016 KB5073722 14393.8783 1 51 53
SQL Server
SQL Server 2025 KB5073177 17.0.1050.2 · 1 1
SQL Server
SQL Server 2022 KB5072936 16.0.4230.2 · 1 2
SharePoint Server
SharePoint Server Subscription Edition KB5002822 16.0.19127.20442 · 6 8
SharePoint Server
SharePoint Server 2019 KB5002825 16.0.10417.20083 · 7 7
SharePoint Server
SharePoint Server 2016 KB5002828 16.0.5535.1001 · 7 7
Office Online Server
Office Online Server KB5002824 16.0.10417.20083 2 1 3

All updates

All updates:
  • Windows 11 · 24H2, 25H2
    Windows 11 24H2 / 25H2 Windows 11 24H2 / 25H2 Optional preview
    Preview
    KB5074105

    Startup hangs and missing sign-in options addressed

    Adds Windows MIDI and accessibility features, updates Secure Boot on eligible 24H2 devices, and addresses issues including startup hangs and missing sign-in options.

    Builds 26100.7705 26200.7705
    Security 1 CVE
    Replaced by KB5077181 →
  • SQL Server · CU1
    SQL Server 2025 CU1 SQL Server 2025 CU1 Cumulative update
    KB5078298

    Database Mail restored; parallel SESSION_CONTEXT issue remains

    This CU restores Database Mail functionality broken by the initial CU1 release and includes 16 fixes. Queries using SESSION_CONTEXT in parallel plans can still return incorrect results or cause access violation dump files.

    Build 17.0.4006.2
    Known issues 1 open
    Replaced by KB5075211 →
  • SQL Server · CU23
    SQL Server 2022 CU23 SQL Server 2022 CU23 Cumulative update
    KB5078297

    Database Mail restored; parallel SESSION_CONTEXT issue remains

    CU23 restores Database Mail functionality broken by the initial release and includes 15 fixes. Queries using SESSION_CONTEXT in parallel plans can still return incorrect results or trigger access violation dumps.

    Build 16.0.4236.2
    Known issues 1 open
    Replaced by KB5077464 →
  • .NET Framework · 3.5, 4.8.1
    .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows 11 25H2 Optional preview
    Preview
    KB5074828

    ClickOnce gains SHA384 and SHA512 checks; ARM64 CLR crash addressed

    Adds SHA384 and SHA512 verification support for ClickOnce and addresses a case where the .NET runtime could crash on ARM64 devices.

    Builds 4.8.9325.0 2.0.50727.9180
    Replaced by KB5082417 →
  • .NET Framework · 3.5, 4.8.1
    .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows 11 24H2 Optional preview
    Preview
    KB5074831

    ClickOnce hash checks added; arm64 runtime crash addressed

    Adds ClickOnce verification for SHA384 and SHA512 and addresses an issue that could crash the .NET runtime on arm64 devices.

    Builds 4.8.9324.0 2.0.50727.9180
    Replaced by KB5082420 →
  • Windows 11 · 26H1
    Windows 11 Windows 11 Insider 26H1 Insider Preview
    Experimental Channel
    Build 28020.1495

    Windows Update settings and shutdown fixes

    Build 28020.1495 for the Experimental Channel notes .webp desktop-background support added in recent Canary builds and includes fixes for Settings, shutdown, pen inking, and other issues.

    Changes 1 improved · 6 fixes
  • Windows 11 · 26H2
    Windows 11 Windows 11 Insider 26H2 Insider Preview
    Experimental Channel
    Build 26300.7674

    Archive extraction and secondary-monitor display fixes

    Dev Channel Insiders get build 26300.7674, with the same features and improvements as build 26220.7653 and gradual fixes for several issues.

    Package KB5074170
    Changes 7 fixes
  • Windows 11 · 25H2
    Windows 11 Windows 11 Insider 25H2 Insider Preview
    Beta Channel
    Build 26220.7670

    Black-screen monitor and virtual desktop sign-in fixes

    Build 26220.7670 for Beta Channel Insiders includes fixes for black-screen monitors, virtual desktop sign-in failures, and other issues. Five known issues remain, including problems with Start and File Explorer.

    Package KB5074169
    Changes 7 fixes
  • Windows 11 · 24H2, 25H2
    Windows 11 24H2 / 25H2 Windows 11 24H2 / 25H2 Out-of-band update
    Out-of-band
    KB5078127

    Cloud-file errors and Outlook hangs fixed

    Some apps and Outlook setups can open or save cloud files again after errors and hangs began with January updates. This out-of-band update adds that fix.

    Builds 26100.7628 26200.7628
    Known issues 1 open
    Replaced by KB5074105 →
  • Windows 11 · 23H2
    Windows 11 23H2 Windows 11 23H2 Out-of-band update
    Out-of-band
    KB5078132

    Cloud-file errors and OneDrive-hosted Outlook hangs fixed

    Fixes file and Outlook problems affecting some cloud-storage users after the January 13 update. Devices with Virtual Secure Mode enabled might still restart instead of shutting down or hibernating; KB5075941 resolves that issue.

    Build 22631.6495
    Known issues 1 open
    Replaced by KB5075941 →
  • Windows 10 · 21H2, 22H2
    Windows 10 21H2 / 22H2 Windows 10 21H2 / 22H2 Out-of-band update
    Out-of-band
    KB5078129

    Cloud-file errors and Outlook hangs fixed

    Fixes errors affecting some apps that open or save cloud-stored files, including Outlook hangs in certain configurations. Some PCs with Virtual Secure Mode enabled might still restart instead of shutting down; KB5075912 resolves that issue.

    Builds 19044.6812 19045.6812
    Replaced by KB5075912 →
  • Windows 10 · 1809
    Windows 10 1809 Windows 10 1809 Out-of-band update Also for Windows Server
    Out-of-band
    KB5078131

    Cloud-file errors and Outlook hangs fixed

    Fixes file access errors in cloud storage and hangs in some Outlook setups that store PST files on OneDrive. A restart is required.

    Build 17763.8281
    Replaced by KB5075904 →
  • Windows Server · 2025
    Windows Server 2025 Windows Server 2025 Out-of-band update
    Out-of-band
    KB5078135

    Cloud-file errors and Outlook hangs fixed; WSUS details remain missing

    Fixes errors opening or saving cloud-based files, including Outlook hangs in some OneDrive PST configurations. WSUS synchronization error details remain unavailable.

    Build 26100.32236
    Known issues 1 open
    Replaced by KB5075899 →
  • Windows Server · 2022
    Windows Server 2022 Windows Server 2022 Out-of-band update
    Out-of-band
    KB5078136

    Cloud-file errors and Outlook hangs get a fix

    Apps that open or save files in cloud storage might stop responding after the January 13 update. This out-of-band update fixes that problem, including hangs in some Outlook setups.

    Build 20348.4651
    Known issues 1 open
    Replaced by KB5075906 →
  • Windows Server · 2019
    Windows Server 2019 Windows Server 2019 Out-of-band update Also for Windows 10
    Out-of-band
    KB5078131

    Cloud-file errors and Outlook hangs fixed

    Fixes file access problems that could leave some apps unresponsive and cause Outlook to hang when PST files are stored on OneDrive.

    Build 17763.8281
    Replaced by KB5075904 →
  • Windows 11 · 24H2, 25H2
    Windows 11 24H2 / 25H2 Windows 11 24H2 / 25H2 Out-of-band update
    Out-of-band
    KB5077744

    Remote Desktop sign-in failures corrected

    Remote Desktop connections work again for users who could not sign in after the January 13 update. Some lock-screen password icons and cloud-storage apps may still have problems.

    Builds 26100.7627 26200.7627
    Known issues 2 open
    Replaced by KB5078127 →
  • Windows 11 · 23H2
    Windows 11 23H2 Windows 11 23H2 Out-of-band update
    Out-of-band
    KB5077797

    Remote Desktop sign-in failures and shutdown restarts get fixes

    Some Remote Desktop sign-ins fail, and some Secure Launch devices restart instead of shutting down or hibernating. This out-of-band update addresses both problems.

    Build 22631.6494
    Known issues 2 open
    Replaced by KB5078132 →
  • Windows 10 · 21H2, 22H2
    Windows 10 21H2 / 22H2 Windows 10 21H2 / 22H2 Out-of-band update
    Out-of-band
    KB5077796

    Remote Desktop sign-in failures fixed; cloud app hangs remain

    Remote Desktop sign-in failures are fixed, but some apps may still hang when opening or saving cloud files. The update also improves Azure checks in the servicing stack.

    Builds 19044.6811 19045.6811
    Known issues 1 open
    Replaced by KB5078129 →
  • Windows 10 · 1809
    Windows 10 1809 Windows 10 1809 Out-of-band update Also for Windows Server
    Out-of-band
    KB5077795

    Remote Desktop sign-ins fixed; cloud-file hangs remain possible

    Some users can sign in over Remote Desktop again. Apps may still hang when opening or saving cloud files, and the update also improves the servicing stack.

    Build 17763.8280
    Known issues 1 open
    Replaced by KB5078131 →
  • Windows Server · 2025
    Windows Server 2025 Windows Server 2025 Out-of-band update
    Out-of-band
    KB5077793

    Remote Desktop sign-in failures fixed

    Remote Desktop connections work again for users who had sign-in failures after the January security update. The update also includes a servicing stack improvement.

    Build 26100.32234
    Known issues 2 open
    Replaced by KB5078135 →
  • Windows Server · 2022
    Windows Server 2022 Windows Server 2022 Out-of-band update
    Out-of-band
    KB5077800

    Remote Desktop sign-ins work again after the January update

    A sign-in failure affecting some Remote Desktop apps after the January 13 security update is fixed. The package also includes servicing stack improvements.

    Build 20348.4650
    Known issues 2 open
    Replaced by KB5078136 →
  • Windows Server · 2019
    Windows Server 2019 Windows Server 2019 Out-of-band update Also for Windows 10
    Out-of-band
    KB5077795

    Remote Desktop sign-in failures fixed

    Fixes sign-in failures during Remote Desktop connections, including with the Windows App. It also includes servicing stack improvements.

    Build 17763.8280
    Known issues 1 open
    Replaced by KB5078131 →
  • Windows 11 · 25H2
    Windows 11 Windows 11 Insider 25H2 Insider Preview
    Beta Channel
    Build 26220.7653

    Dark-mode account dialogs and fixes for taskbar and Start

    Brings redesigned account dialogs, .webp desktop backgrounds, and fixes for taskbar, Start, Settings, and other issues to Windows Insiders in the Beta and Dev Channels.

    Package KB5074157
    Changes 1 new · 2 improved · 14 fixes
  • Windows 11 · 26H1
    Windows 11 Windows 11 Insider 26H1 Insider Preview
    Experimental Channel
    Build 28020.1371

    Start menu, File Explorer and keyboard behavior fixes

    Build 28020.1371 for Canary Channel Insiders fixes several Start menu, File Explorer, keyboard, Windows Terminal and sharing issues. The fixes are rolling out gradually with the toggle on.

    Changes 5 fixes
  • Windows 11 · 24H2, 25H2
    Windows 11 24H2 / 25H2 Windows 11 24H2 / 25H2 Security update
    Zero-day
    KB5074109

    Exploited Desktop Window Manager flaw patched; modem drivers removed

    The update patches an actively exploited flaw in Desktop Window Manager and removes four older modem drivers, which can leave dependent modem hardware unusable.

    Builds 26100.7623 26200.7623
    Security 86 CVEs 3 critical 1 exploited
    Known issues 3 open
    Replaced by KB5077744 →