Is It Safe to Install Windows 11 KB5074109 on Version 25H2 Today?

Why Is the January 2026 Windows 11 Update File Size Over 4GB?

Windows 11 KB5074109: January 2026 Security Update Overview

Microsoft has released the first major update of the year, KB5074109, for Windows 11 versions 25H2 and 24H2. This “Patch Tuesday” release focuses primarily on security improvements and bug fixes, though it also enables specific features for eligible devices.

This is a mandatory security update. Your system will download and install it automatically within the next 24 hours. In Windows Update, you will see this labeled as:

• 2026-01 Security Update (KB5074109) (26200.7623)

Direct Download Links

If Windows Update fails or you need to deploy this patch across multiple offline machines, you can use the Microsoft Update Catalog.

• Download: Windows 11 KB5074109 Offline Installers (.msu)

Build Numbers and File Size

This update increases the file size for all users because Microsoft now bundles local AI models (such as Phi) directly into the operating system. Even if your hardware does not support NPU acceleration, these models are included in the package foundation.

Note: Versions 25H2 and 24H2 share an identical core operating system. The changes listed below apply to both versions.

Critical Fixes in KB5074109

The January 2026 update resolves several technical issues that disrupted workflows in late 2025.

Networking and Virtualization Repairs

WSL VPN Connectivity: Microsoft fixed a bug where the Windows Subsystem for Linux (WSL) failed to access resources while a VPN was active.

Azure Virtual Desktop (AVD): Remote Desktop sessions within Fixed AVD environments no longer trigger connection errors.

Security and Driver Updates

Legacy Driver Removal: To harden security, Microsoft removed outdated drivers including agrsm64.sys, agrsm.sys, smserl64.sys, and smserial.sys. Modern networking alternatives now handle these functions.

WinSqlite3.dll: The update patches vulnerabilities within this standard SQL database component.

Secure Boot Certificates: Enterprise devices will receive updated Secure Boot keys. This rollout targets specific eligible business machines first.

Hardware Performance

NPU Power Drain: A fix addresses an issue where the Neural Processing Unit (NPU) consumed excessive power, draining batteries on AI-enabled laptops.

High-Res Monitor Stutter: Launching games on high-resolution displays no longer causes stuttering during the “monitor query” phase.

Backlit Keyboards: HID-compliant keyboards now manage backlight performance more efficiently.

New Features Rolling Out (Phased Release)

While KB5074109 is a maintenance release, it triggers the activation of several features previously in testing. You may not see these immediately, as Microsoft activates them gradually via server-side switches.

Taskbar and AI Integration

“Share with Copilot”: Hovering over a taskbar app icon now reveals a “Share with Copilot” option. This allows you to instantly share that specific window with the AI assistant for analysis or queries.

• Privacy Note: You can disable this via Settings > System > Taskbar > Taskbar behavior.

Colorful Battery Icons: The system tray battery indicator may now utilize a color-coded status depending on charge levels.

File Explorer Enhancements

Consistent Dark Mode: Legacy dialog boxes (file transfers, delete confirmations, and error messages) now correctly respect the system-wide Dark Mode theme.

Recommended Feed: Users with Microsoft accounts or Entra IDs (Work accounts) will see a “Recommended” file section in Explorer. This can be toggled via Folder Options.

System Settings Migration

Microsoft continues to retire the Control Panel. You can now manage the following advanced tools directly through the Settings app under System > Advanced Settings:

• Windows Sandbox
• Hyper-V
• Virtual Workspaces

Gaming Handheld Mode

For users on handheld gaming PCs (like the ROG Ally or Legion Go), this update enables Full Screen Experience.

Location: Settings > Gaming > Full screen experience.

Function: This minimizes background processes and forces the Xbox app UI to take precedence, optimizing RAM and CPU resources for gaming performance.

Known Issues

Before installing, be aware of the following persistent bug:

• Lock Screen Icon: The password field icon may disappear on the lock screen. This is a visual glitch present since August 2025 and does not affect the ability to log in.

Advisory: We recommend installing this update immediately to ensure your system is protected against the patched security vulnerabilities.