Windows 11 KB5074109: Patch Tuesday Build 26200.7623

• Key Takeaways:
• Microsoft released Windows 11 KB5074109 (January 2026 Patch Tuesday); it advances 25H2 to Build 26200.7623 (24H2 to 26100.7623).
• The update is mandatory and will download/install automatically unless updates are paused; offline .msu installers are available from the Microsoft Update Catalog.
• KB5074109 focuses on bug fixes (WSL VPN, Azure Virtual Desktop, NPU power), security updates (WinSqlite3.dll), and bundles AI model assets — update size exceeds 3.9–4.3 GB.
• Some feature rollouts continue (Share with Copilot on the taskbar, Recommended feed in File Explorer, dark mode fixes, handheld full-screen mode).

What KB5074109 delivers

Microsoft’s January 2026 update (KB5074109) is a maintenance release for Windows 11 25H2 and 24H2. Installing the patch moves systems to Build 26200.7623 (25H2) or 26100.7623 (24H2).

How to get the update

KB5074109 is distributed via Windows Update and installs automatically unless you pause updates. If you prefer an offline installer or manage multiple machines, use the Microsoft Update Catalog: https://www.catalog.update.microsoft.com/Search.aspx?q=KB5074109

Download size and timing

The update is large because Microsoft now includes AI model components (for example, Phi-related assets). Typical sizes reported are ~4,270 MB for x64 and ~3,950 MB for arm64. Installation times vary by hardware and network speed.

Key fixes and security changes

KB5074109 is primarily a bug-fix release with several targeted patches and security improvements.

Notable fixes

- Resolved an issue where Windows Subsystem for Linux (WSL) could not access resources over a VPN following prior security updates.

- Fixed errors affecting Fixed Azure Virtual Desktop (AVD) environments when using Remote Desktop.

- Addressed a case where neural processing units (NPU) were negatively impacting power efficiency on some devices.

- Updated WinSqlite3.dll with security hardening.

Removed drivers and enterprise changes

Microsoft has removed several legacy/modern drivers (agrsm64.sys, agrsm.sys, smserl64.sys, smserial.sys) and began rolling out new Secure Boot certificates to eligible enterprise devices.

Features still rolling out

Some user-facing features continue to be staged and may appear after installing this update:

- Share with Copilot

A new taskbar toggle that lets apps share their window directly with Copilot via a new Windows API is rolling out to more devices.

- File Explorer improvements

A Recommended feed and dark mode consistency fixes are being distributed to more users.

- Other updates

Advanced Settings controls (Sandbox, Hyper-V), full-screen mode for handhelds, and monitor-query performance improvements are also part of the staged rollout.

Known issues

Microsoft reports no new widespread issues tied directly to KB5074109. If you rely on mission-critical systems, test the update in a controlled environment before broad deployment and monitor vendor advisories.

For enterprises and administrators, consult the Update Catalog link above and Microsoft’s release notes for details tailored to your environment.