Update09/10/2025

KB5065432: App compatibility (known issue) Fixed

Windows Server 2022
Microsoft

Update from:
patrick-devicebase (expert)

September 9, 2025—KB5065432 (OS Build 20348.4171)

Improvements
This security update contains fixes and quality improvements from KB5063880 (released August 12, 2025). The following summary outlines key issues addressed by this update. Also, included are available new features. The bold text within the brackets indicates the item or area of the change.

[App compatibility (known issue)] Fixed: Addresses an issue that caused non-admin users to receive unexpected User Account Control (UAC) prompts when MSI installers perform certain custom actions. These actions might include configuration or repair operations in the foreground or background, during the initial installation of an application.

This issue could prevent non-admin users from running apps that perform MSI repairs, including Office Professional Plus 2010 and multiple applications from Autodesk (including AutoCAD). This fix reduces the scope for requiring UAC prompts for MSI repairs and enables IT admins to disable UAC prompts for specific apps by adding them to an allowlist.

For more information, see Unexpected UAC prompts when running MSI repair operations after installing the August 2025 Windows security update.

[File server] This update enabled auditing SMB client compatibility for SMB Server signing as well as SMB Server EPA. This allows customers to assess their environment and identify any potential device or software incompatibility issues before deploying the hardening measures that are already supported by SMB Server. For detailed guidance, see CVE-2025-55234.
[Input] Fixed: This update addresses an issue with the Chinese (Simplified) Input Method Editor (IME) where some extended characters appeared as empty boxes.
[Performance] Fixed: This update addresses an issue where a single, oversized Certificate Revocation List (CRL) file slows down system performance. To improve speed and privacy, the system now plans to use smaller, partitioned CRLs.

Known issues in this update
PSDirect connections failing in hotpatched devices
Symptoms
We are aware of an edge case affecting hotpatched devices that have installed the September 2025 Hotpatch update (KB5065306) or the September 2025 security update (KB5065432). These devices may experience failures with PowerShell Direct (PSDirect) connections when the host and guest virtual machines (VMs) are both not fully updated.

When a patched guest VM attempts to connect to an unpatched host (or vice versa), the system is expected to fall back to a legacy handshake and clean up the socket gracefully. However, this fallback mechanism fails intermittently, resulting in socket cleanup issues. The connection failure might appear random, and users might observe Event ID 4625 logged in the Security Event log within Windows Event Viewer.

Workaround
This issue is addressed in KB5066359. If your hotpatched device is experiencing issues with PSDirect connection, we recommend updating both the host and guest VM with these updates.