Microsoft released cumulative security update KB5079466 (Build 28000.1719) for Windows 11 version 26H1 as part of the March 2026 Patch Tuesday for PCs with ARM processors.
This update includes all fixes and changes from preview version KB5077239 (Build 28000.1643) Preview for Windows 11 26H1, including expanded AI agent capabilities in the Settings app, an updated Click to Do menu, File Explorer improvements, new Windows Share features, Virtual Workspaces support, enhanced Cross-Device Resume capabilities, Windows MIDI Services updates, accessibility improvements (Narrator, Voice Access, and voice typing), as well as numerous stability fixes, including improvements to BitLocker, graphics, taskbar, and lock screen.
- Windows Defender Application Control. Improved handling of allowed COM object policies (allowlisting) in Windows Defender Application Control (WDAC). Previously, COM objects could be blocked if the endpoint security policy was stricter than the allowlisting policy. After the update, COM objects are allowed correctly.
- Windows System Image Manager. Increased reliability when selecting trusted catalog files. Added a warning dialog box to help ensure that the selected file comes from a trusted source.
The update is installed via Windows Update. To do this, go to Settings > Windows Update and click Check for updates. A system restart is required to complete installation.
Important note: automatic installation via Windows Update only works on devices with ARM processors.
| Feature / Change | Performance Impact | Optimization | PC Speed | Gaming Optimization |
|---|---|---|---|---|
| Windows Defender Application Control (WDAC) — improved COM object allowlisting | 🟢 Low improvement (reduces unnecessary blocking overhead) | 🟢 High (correct policy enforcement reduces false positives) | 🟢 Minor (fewer interruptions from blocked COM objects) | ⚪ No direct impact |
| Windows System Image Manager — trusted catalog file reliability | ⚪ No impact | 🟡 Medium (safer file selection for imaging) | ⚪ No impact | ⚪ No impact |
Find and Change Settings
| Setting | Where to find | How to change |
|---|---|---|
| Windows Defender Application Control (COM object allowlisting) | Endpoint security policy (Intune or Group Policy) > Windows Defender Application Control | Update your WDAC policy to the latest version. Ensure your allowlisting policy for COM objects is properly configured. After the update, COM objects that match the allowlist will be permitted even if the broader endpoint security policy is stricter. No manual change is required for the fix, but you may need to redeploy the updated policy. |
| Windows System Image Manager (trusted catalog files) | Windows System Image Manager > Select catalog file | When selecting a catalog file, a warning dialog box will now appear. Confirm that the file comes from a trusted source before proceeding. The reliability of selecting trusted catalog files has been increased; no additional configuration is needed. |
Official announcement on the Microsoft website.
The last 10 Windows updates:
| Update | Build | Version | Windows | Channel | Date |
|---|---|---|---|---|---|
| KB5121157 | 28020.2818 | 26H1 | Windows 11 | Beta | 2026-08-31 |
| KB5121158 | 28120.2824 | 26H1 | Windows 11 | Experimental | 2026-08-31 |
| KB5121794 | 26300.9278 | 26H2 | Windows 11 | Preview | 2026-08-27 |
| KB5121132 | 28120.2760 | 26H1 | Windows 11 | Experimental | 2026-08-21 |
| KB5124040 | 26220.9223 | 25H2 | Windows 11 | Beta | 2026-08-21 |
| KB5124042 | 26340.9233 | 26H2 | Windows 11 | Experimental | 2026-08-21 |
| KB5121106 | 28020.2731 | 26H1 | Windows 11 | Beta | 2026-08-17 |
| KB5121109 | 28120.2738 | 26H1 | Windows 11 | Experimental | 2026-08-17 |
| KB5124036 | 26220.9202 | 25H2 | Windows 11 | Beta | 2026-08-17 |
| KB5124038 | 26340.9212 | 26H2 | Windows 11 | Experimental | 2026-08-17 |