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Windows 11 26H1 Windows 11 26H1 Security update
Patch Tuesday

KB5079466

KB5079466: Cumulative update for Windows 11, version 26H1, March 2026. Secure Boot certificate rollout expands; COM allowlisting works as expected

In short

The update expands the phased delivery of new Secure Boot certificates and improves COM allowlisting in Windows Defender Application Control. It also includes 40 Important-severity security fixes.

Does it affect you? Applies to: Devices running Windows 11, version 26H1, with x64 or Arm64 processors. The AI component updates apply only to Copilot+ PCs.

Build
28000.1719
Security
40 fixed
Restart
Required

What changes

Improvements 5 changes

Secure Boot

Gradual rollout Verified in package

For: Devices eligible for new Secure Boot certificates

  • More eligible devices can receive new Secure Boot certificates automatically, after showing enough successful update signals.1
    Windows quality updates include additional high confidence device targeting data to increase coverage while maintaining a controlled, phased rollout.

Windows Defender Application Control

For: Devices using COM objects allowlisting policies

  • COM objects are allowed as expected when the endpoint security policy is set higher than the allowlisting policy.2
    Improves how Windows Defender Application Control (WDAC) handles COM objects allowlisting policies.

Windows System Image Manager

For: People choosing catalog files

  • A warning dialog helps you check that a catalog file you select comes from a trusted source.3
    Improves the reliability of choosing trusted catalog files.

AI components

Verified in package
  • Four AI components receive updates on Copilot+ PCs.4
    Image Search, Content Extraction, Semantic Analysis, and Settings Model are updated to version 1.2601.1268.0. These components do not install on other Windows PCs or Windows Server.

Servicing stack

  • The component that installs Windows updates receives quality improvements.5
    Includes servicing stack update KB5078262, build 28000.1638.

Technical details

Data sheet · Security · Downloads · Components Click to collapse or expand

Data sheet

Released
2026-03-10
Classification
Security Updates
Type
Cumulative update
Restart
Required
Replaces
KB5077239, KB5077179
Replaced by
KB5083768
VersionBuildChannel
26H1 28000.1719 General availability
26H1 28000.1719 Release Preview Channel

Security

40 vulnerabilities fixed
40 important
VulnerabilitySeverityCVSS

The table lists the 0 exploited, publicly disclosed or critical vulnerabilities. See all 40 vulnerabilities →

Updated components

2,016 files changed since the previous update for the same versions.

Top changed componentsFiles
Audio18
File Explorer and shell17
Networking15
Graphics and display12
Secure Boot9
Settings8
Kernel5
Hyper-V and virtualization4
Storage and file systems4
Bluetooth3
Printing3
Search3

Verified in package: changed files confirm Secure Boot, AI components.

Sources

Updated
Cited passages from Microsoft's official notes (5)
  1. 1. With this update, Windows quality updates include additional high confidence device targeting data, increasing coverage of devices eligible to automatically receive new Secure Boot certificates. support.microsoft.com
  2. 2. With this update, COM objects are allowed as expected. support.microsoft.com
  3. 3. It adds a warning dialog that helps you confirm that the file you select comes from a trusted source. support.microsoft.com
  4. 4. Image Search | 1.2601.1268.0 support.microsoft.com
  5. 5. This update makes quality improvements to the servicing stack, which is the component that installs Windows updates. support.microsoft.com
Checked automatically: 7 of 8 checks passed, 5 quoted passages · compared with Microsoft's page on Oct 20, 2026
  • Quotes found in the official pages: passed
  • Numbers found in the sources: passed
  • Vulnerabilities from the dossier only: passed
  • Links to allowed domains only: passed
  • Every official change covered: passed
  • Readable plain text: passed
  • Changes confirmed by the file list: passed
  • Sources agree: not passed

A second AI read the text against the sources: correctness 4/5, clarity 4/5, completeness 5/5. How we work

Published by The Update Bureau. Written with AI from Microsoft's own documents, checked by rules and a second AI. How we work · Report a mistake