KB5066586: Fixed: An issue with the Chinese Input Method Editor

October 14, 2025—KB5066586 (OS Build 17763.7919)

Applies to: Windows Server 2019 (All editions)

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

• September 9, 2025—KB5065428 (OS Build 17763.7792)

The following is a summary of the issues that this update addresses when you install this update. The bold text within the brackets indicates the item or area of the change we are documenting

​​​[Input and Composition]

• Fixed: An issue with the Chinese Input Method Editor (IME). Private Unicode characters were shown incorrectly and did not meet GB18030 standard.
• Fixed: An issue that affects USER32 Edit controls. Surrogate pairs appear as empty boxes when text fields reach their length limit.

[Windows Remote Management (WinRM)]

• Fixed: An issue that affects PowerShell Remoting and WinRM in which commands time out after 600 seconds.

[Stability issue]

• Fixed: 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. Some devices became unresponsive and stopped responding in specific scenarios.

[Fax modem driver]

• This update removes the ltmdm64.sys driver. Fax modem hardware dependent on this specific driver will no longer work in Windows.