January 24, 2026—Hotpatch KB5078238 (OS Build 20348.4655) Out-of-band

This out-of-band Hotpatch update for Windows Server 2022 (KB5078238), improves functionality, performance, and reliability. To learn more about differences between security updates, optional non-security preview updates, out-of-band (OOB) updates, and continuous innovation, see Windows monthly updates explained. For information on Windows update terminology, see the different types of Windows software updates.

To view the latest updates about this release, visit the Windows release health dashboard or the update history page for Windows Server 2022.

Announcements and messages

This section provides key notifications related to this release, including announcements, change logs, and end-of-support notices.

Windows Secure Boot certificate expiration

Important: Secure Boot certificates used by most Windows devices are set to expire starting in June 2026. This might affect the ability of certain personal and business devices to boot securely if not updated in time. To avoid disruption, we recommend reviewing the guidance and taking action to update certificates in advance. For details and preparation steps, see Windows Secure Boot certificate expiration and CA updates.

Improvements and fixes

This out-of-band Hotpatch update includes security and quality improvements. The following summary outlines key issues addressed by this update. The bold text within the brackets indicates the item or area of the change.

[Remote Desktop] Fixed: Some users experienced sign-in failures during Remote Desktop connections. This issue affected authentication steps for different Remote Desktop applications on Windows such as the Windows App.
[File System] Fixed: After installing the Windows update released on and after January 13, 2026, some applications became unresponsive or encountered unexpected errors when opening files from or saving files to cloud-based storage, such as OneDrive or Dropbox. In certain Outlook configurations that store PST files on OneDrive, Outlook may hang and fail to reopen unless the process is terminated or the system is restarted. Users may also see missing sent Items or previously downloaded emails being re‑downloaded.

If you've already installed previous updates, your device will download and install only the new updates included in this package.

Note: This hotpatch update will install and take effect without requiring you to restart the device. For more information see Hotpatch updates.

Known issues in this update

After installing KB5070892 or later updates, Windows Server Update Services (WSUS) does not display synchronization error details within its error reporting. This functionality is temporarily removed to address the Remote Code Execution Vulnerability, CVE-2025-59287.

How to get this update

Before you install this update

Microsoft now combines the latest servicing stack update (SSU) for your operating system with the Hotpatch update. For general information about SSUs, see Servicing stack updates and Servicing Stack Updates (SSU): Frequently Asked Questions.

If you are using Windows Update or Windows Server Update Services (WSUS), the latest SSU installs with this update.

Install this update

To install this update, use one of the following Windows and Microsoft release channels.