KB5066782: Cumulative update for Windows Server, version 2022, October 2025. Exploited Remote Access flaw addressed; downloaded-file previews disabled

The update addresses security vulnerabilities, including exploited flaws, and changes File Explorer so it disables previews of files downloaded from the internet. It also fixes several server issues and removes a fax modem driver.

Does it affect you? Applies to: Devices running Windows Server 2022, x64.

What changes

Fixes 6 changes

Input

2 items

Some characters display correctly again when you use the Chinese Input Method Editor.¹
Certain Chinese characters no longer appear as empty boxes in some text fields when a character limit is set.²
The issue affected fields such as those used in Connection Manager Administration Kit.

Networking

Verified in package

For: devices using SMB v1 on NetBT

The update addresses a problem that could prevent access to shared files and folders.³
The issue could occur when using SMB v1 on NetBIOS over TCP/IP (NetBT), after installing KB5065432.

PowerShell

For: devices using PowerShell Remoting or Windows Remote Management

PowerShell Remoting and Windows Remote Management commands might no longer time out after 10 minutes.⁴

Stability

The update addresses rare cases where devices became unresponsive in specific scenarios.⁵
The issue was observed after installing the May 2025 security update and subsequent updates.

System services and reliability

The McpManagement service no longer appears without a description in Windows.⁶

Improvements 3 changes

Cryptography

RSA-based smart card certificates now use a security-hardened method, which might affect smart card authentication.⁷
Use of Key Storage Provider (KSP) is required instead of Cryptographic Service Provider (CSP) for RSA-based smart card certificates. The page points to Windows Release Health for resolution steps if authentication problems occur.

File Explorer

File Explorer automatically disables previews for files downloaded from the internet, helping prevent a vulnerability when previewing potentially unsafe files.⁸
The page links to instructions for unblocking files when needed.

Servicing stack

The update includes quality improvements to the component that installs Windows updates.⁹
The combined package includes servicing stack update KB5066781, build 20348.4285.

Removal 1 change

Compatibility

For: devices with fax modem hardware dependent on ltmdm64.sys

Fax modem hardware that depends on the ltmdm64.sys driver will no longer work in Windows.¹⁰
This update removes the ltmdm64.sys driver.

Technical details

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

Data sheet

Released: 2025-10-14
Classification: Security Updates
Type: Cumulative update
Restart: Required
Replaces: KB5065432, KB5063880, KB5062572, KB5060526

+24 earlier
KB5061906, KB5058385, KB5059092, KB5058920, KB5055526, KB5053603, KB5051979, KB5052819, KB5049983, KB5048654, KB5046616, KB5047767, KB5044281, KB5042881, KB5041160, KB5040437, KB5041054, KB5039227, KB5037782, KB5036909, KB5037422, KB5035857, KB5034770, KB5034129
Replaced by: KB5070884

Version	Build	Channel
2022	20348.4294	General availability

Security

104 vulnerabilities fixed

3 exploited 2 critical 102 important

Vulnerability	Severity	CVSS
CVE-2025-24990 Exploited Windows Agere Modem Driver Elevation of Privilege Vulnerability	Important	7.8
CVE-2025-59230 Exploited Windows Remote Access Connection Manager Elevation of Privilege Vulnerability	Important	7.8
CVE-2025-47827 Exploited MITRE CVE-2025-47827: Secure Boot bypass in IGEL OS before 11	Important	4.6
CVE-2025-49708 Microsoft Graphics Component Elevation of Privilege Vulnerability	Critical	9.9
CVE-2016-9535 MITRE CVE-2016-9535: LibTIFF Heap Buffer Overflow Vulnerability	Critical	4.0
CVE-2025-24052 Windows Agere Modem Driver Elevation of Privilege Vulnerability	Important	7.8

The table lists the 6 exploited, publicly disclosed or critical vulnerabilities. See all 104 vulnerabilities →

Downloads (Microsoft Update Catalog)

x64 2022

408.3 MB

windows10.0-kb5066782-x64.msu Main update · KB5066782 SHA-1: 4fe4cee2…557c2f

Updated components

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

Top changed components	Files
Networking	13
Graphics and display	11
Security and sign-in	8
Hyper-V and virtualization	7
Printing	7
Secure Boot	7
Storage and file systems	7
Kernel	6
Remote Desktop	6
Search	5
File Explorer and shell	4
Windows Update	4

Verified in package: changed files confirm Networking.

Sources

Microsoft Support: KB5066782

Updated Oct 27, 2026

Cited passages from Microsoft's official notes (10)

1. Fixed: An issue where some characters didn’t display correctly when using the Chinese Input Method Editor (IME). support.microsoft.com
2. Fixed: This update addresses an issue where certain Chinese characters appeared as empty boxes in some text fields, such as those used in Connection Manager Administration Kit, when a character limit was set. support.microsoft.com
3. Fixed: This update addresses an issue where you might not be able to connect to shared files and folders if you're using the Server Message Block (SMB) v1 protocol on NetBIOS over TCP/IP NetBIOS (NetBT). support.microsoft.com
4. This update addresses an issue that affects PowerShell Remoting and Windows Remote Management (WinRM), where commands might time out after 10 minutes. support.microsoft.com
5. This update addresses an issue observed in rare cases after installing the May 2025 security update and subsequent updates causing devices to experience stability issues. support.microsoft.com
6. Addresses an issue that caused McpManagement service to appear without a description on Windows. support.microsoft.com
7. This update enforces a security hardening improvement by requiring use of Key Storage Provider (KSP) instead of Cryptographic Service Provider {CSP) for RSA-based smart card certificates. support.microsoft.com
8. After installing this update, File Explorer automatically disables the preview feature for files downloaded from the internet. support.microsoft.com
9. This update makes quality improvements to the servicing stack, which is the component that installs Windows updates. support.microsoft.com
10. This update removes the ltmdm64.sys driver. Fax modem hardware dependent on this specific driver will no longer work in Windows. support.microsoft.com

Checked automatically: 8 of 8 checks passed, 10 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 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