KB5066791: Overview with user sentiment and feedback

Overview

This article lists the security issues and quality improvements included in this security update. Windows 10, version 21H2 and Windows 10, version 22H2 are affected.

General Purpose

This security update includes fixes and quality improvements that are part of the following updates:

• September 9, 2025—KB5065429 (OS Builds 19044.6332 and 19045.6332)
• September 25, 2025—KB5066198 (OS Build 19045.6395)

The update addresses issues in the following areas:

• [Input and Composition] Fixed issues with the Chinese Input Method Editor (IME) and USER32 Edit controls.
• [Windows Remote Management (WinRM)] Fixed an issue that affects PowerShell Remoting and WinRM where commands time out after 600 seconds.
• [Licensing] This update introduces a servicing stack update (SSU) which incorporates an updated certificate chain to improve Azure environment validation.
• [Fax modem driver] This update removes the ltmdm64.sys driver, so fax modem hardware dependent on this driver will no longer work.
• [Cryptography] 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.
• [File Explorer] This update automatically disables the preview feature for files downloaded from the internet to enhance security.

General Sentiment

The general sentiment towards this update is mixed. While it includes several important fixes and security improvements, there are also known issues that may cause problems for some users. The update introduces a change to require Key Storage Provider (KSP) instead of Cryptographic Service Provider (CSP) for RSA-based smart card certificates, which could cause authentication issues for some users. Additionally, there is a known issue where an incorrect "End of Support" message may incorrectly display for certain Windows 10 versions that are still supported.Microsoft has provided workarounds for these issues, but they may not be suitable for all users. Overall, the update appears to be a necessary security release, but users should be aware of the potential problems and take appropriate steps to mitigate any disruptions.

Known Issues

• An incorrect "End of Support" message might appear in Settings for certain Windows 10 versions that are still supported.- Issues with smart card authentication due to the requirement to use Key Storage Provider (KSP) instead of Cryptographic Service Provider (CSP).

Disclaimer: We take measures to ensure that AI-generated content is of the highest possible quality, but we cannot guarantee its accuracy and recommend that users do their own independent research. Generated on 2025-11-29 01:16 PM

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