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Windows Server 2016 Windows Server 2016 Security update
Patch Tuesday

KB5065427

KB5065427: Cumulative update for Windows Server, version 2016, September 2025. SMB compatibility auditing added; MSI repair prompts reduced

In short

Adds a way to audit SMB client compatibility before hardening and reduces unexpected UAC prompts during some MSI actions. The update also addresses 45 vulnerabilities, including five rated critical.

Does it affect you? Applies to: Devices running Windows Server 2016, including Hyper-V Server 2016.

Build
14393.8422
Security
45 fixed · 5 critical
Restart
Required

Microsoft publishes separate notes for this KB for Windows 10.

What changes

Fix 1 change

App compatibility (known issue)

For: non-admin users and IT administrators

  • Non-admin users are less likely to see unexpected UAC prompts during certain MSI installer actions, including repairs.1
    The change reduces the scope of UAC prompts for MSI repairs and enables IT admins to disable prompts for specific allowlisted apps.

New feature 1 change

File Server

  • IT teams can check SMB client compatibility before deploying SMB Server hardening measures.2
    Enables auditing SMB client compatibility for SMB Server signing and SMB Server EPA.

Technical details

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

Data sheet

Released
2025-09-09
Classification
Security Updates
Type
Cumulative update
Restart
Required
Replaces
KB5063871, KB5062560, KB5061010, KB5058383
+8 earlier KB5058921, KB5055521, KB5053594, KB5052006, KB5049993, KB5048671, KB5046612, KB5037423
Replaced by
KB5066836
VersionBuildChannel
2016 14393.8422 General availability

Security

45 vulnerabilities fixed
5 critical 40 important
VulnerabilitySeverityCVSS
CVE-2025-54918
Windows NTLM Elevation of Privilege Vulnerability
 Critical 8.8
CVE-2025-53800
Windows Graphics Component Elevation of Privilege Vulnerability
 Critical 7.8
CVE-2025-48807
Windows Hyper-V Remote Code Execution Vulnerability
 Critical 6.7
CVE-2025-55226
Graphics Kernel Remote Code Execution Vulnerability
 Critical 6.7
CVE-2025-53799
Windows Imaging Component Information Disclosure Vulnerability
 Critical 5.5
CVE-2025-55234
Windows SMB Elevation of Privilege Vulnerability
 Important 8.8

The table lists the 6 exploited, publicly disclosed or critical vulnerabilities. See all 45 vulnerabilities →

Updated components

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

Top changed componentsFiles
Graphics and display7
Networking7
Hyper-V and virtualization6
Remote Desktop6
Secure Boot6
Security and sign-in6
Kernel5
Search4
File Explorer and shell3
Settings2
Storage and file systems2

Sources

Updated
Cited passages from Microsoft's official notes (2)
  1. 1. Fixed: Addresses an issue that caused non-admin users to receive unexpected User Account Control (UAC) prompts when MSI installers perform certain custom actions. support.microsoft.com
  2. 2. This update enables auditing SMB client compatibility for SMB Server signing as well as SMB Server EPA. 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 5/5, 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