KB5079466

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.

How the new features work:

Windows Defender Application Control: In WDAC, COM object validation now uses a two-pass resolution: first checks against the allowlist policy, then against the general security policy. The false-blocking issue due to a stricter endpoint policy is eliminated — an object is allowed if present in at least one allowed list.

Windows System Image Manager: When selecting .cat files, digital signature verification and hash matching against a trusted source are performed. A warning dialog triggered via CryptCATAdminCalcHashFromFileHandle is added, requiring confirmation before applying an unsigned or untrusted catalog.

The last 10 Windows updates: