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Windows Server 2019 Windows Server 2019 Out-of-band update
Out-of-band

KB5066187

KB5066187: Cumulative update for Windows Server, version 2019, August 2025. Secure Boot certificates begin expiring in June 2026

In short

Improves the servicing stack. Secure Boot certificates used by most Windows devices have started expiring in June 2026, so review Microsoft's guidance and prepare to update them.

Does it affect you? Applies to: Windows Server 2019, all supported editions. The available package is for x64.

Build
17763.7683
Restart
Required

Microsoft publishes separate notes for this KB for Windows 10.

What changes

Improvement 1 change

Servicing stack

  • The component that installs Windows updates gets quality improvements intended to make the update process more reliable.1
    The update includes servicing stack update KB5062800 (build 17763.7557).

Known issues

  1. Resolved Affects: Everyone Resolved by KB5065428

    Unexpected User Account Control (UAC) prompt when doing MSI repair operations

    Standard users might see an unexpected UAC prompt during MSI repair and related operations. Updates released on and after September 9, 2025, including KB5065428, resolve the issue.2

    Resolution Fixed in KB5065428

    Install KB5065428 (or a later cumulative update) on affected devices. No manual workaround is required after updating.

Technical details

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

Data sheet

Released
2025-08-19
Classification
Updates
Type
Cumulative update
Restart
Required
Replaces
KB5063877, KB5062557, KB5060531, KB5061978
+5 earlier KB5058392, KB5059091, KB5058922, KB5050008, KB5037425
Replaced by
KB5065428
VersionBuildChannel
2019 17763.7683 General availability

Security

No vulnerabilities are listed for this update.

Downloads (Microsoft Update Catalog)

x64 2019
704.2 MB
windows10.0-kb5066187-x64.msu Main update · KB5066187 SHA-1: c0f01896…9b9f52

Updated components

117 files changed since the previous update for the same versions.

Top changed componentsFiles
Secure Boot3
Hyper-V and virtualization2
Kernel2

Sources

Updated
Cited passages from Microsoft's official notes (2)
  1. 1. This update makes quality improvements to the servicing stack, which is the component that installs Windows updates. support.microsoft.com
  2. 2. This issue is resolved by Windows updates released on and after September 9, 2025 (KB5065428). support.microsoft.com
Checked automatically: 8 of 8 checks passed, 2 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: passed

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