Win Update KB5099536 Windows Server 2025 Cumulative Update build 26100.33158 - July 14

This cumulative update for Windows Server 2025 (KB5099536), includes the latest security fixes and improvements, along with non-security updates from last month’s optional preview release. Visit the Windows release health dashboard for the latest status on this release. For more information, see Windows Secure Boot certificate expiration and CA updates.

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. Microsoft has been updating these certificates on consumer and non-managed business devices over the past several months. Devices that haven’t received the newer certificates will continue to start and operate normally, and standard Windows updates will continue to install. Updated certificates will continue to be delivered through Windows Update in the coming months.

Improvements​

This security update contains fixes and quality improvements from KB5094125 (released June 9, 2026). 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.

• [Secure Boot] This update includes additional high confidence device targeting data, increasing coverage of devices eligible to automatically receive new Secure Boot certificates. Certificate deployment via Windows updates continues across supported PCs and non-managed business devices in the coming months.
• [Apps (Known issue)] Fixed: This update addresses an issue that affects certain third-party apps that use OLE Automation to interact with Microsoft Office. After installing the June 2026 security update (KB5094125), these apps might fail to launch Office or open documents.
• [Containers] This update improves startup performance for Hyper-V–isolated Windows Server containers on Windows Server 2025. The updated Windows Server 2025 container base images (nanoserver, servercore, and windowsservercore) include this improvement and are available through the Microsoft Container Registry (MCR). Pull the latest image tag to get the update.
• [Cryptography]
• This update adds support for hybrid post-quantum cryptography (PQC) key exchange in Transport Layer Security (TLS) 1.3. This enhancement helps protect secure network connections against emerging threats and improves readiness for future security challenges.
• This update adds support for composite cryptographic formats that combine traditional and post-quantum algorithms in a single signature or key.
• [Distributed Key Manager (DKM)] This update introduces automatic detection of insecure DKM container ACL configurations in AD FS and provides an opt-in remediation mechanism to help administrators strengthen DKM container permissions. For more information about how to manage this change, see CVE-2026-56155: AD FS Distributed Key Manager container ACL hardening
• [Event Log] This update improves the reliability of the Windows Event Log service on event collector servers that forward events to custom log channels configured with a manifest.
• [File Explorer (known issue)] Fixed: An issue where the OneDrive shortcut in File Explorer stops working when File Explorer is run with administrative mode.This issue might occur after installing the June 2026 security update (KB5094125).
• [Input] This update changes hotkey unregister and cleanup behavior. In rare cases, some built-in Windows experiences that rely on previous hotkey lifecycle behavior might temporarily stop responding to certain keyboard shortcuts. This issue can typically be resolved by restarting the app affected. If the issue is not resolved, report it through the Feedback Hub.
• [Networking]
• This update improves how your device connects to shared network resources. Connections used by apps and system features, such as the NetUseAdd function, now work more reliably, including unauthenticated (null session) connections.
• This update introduces a security hardening change that enforces TDI transport registration requirements. As a result, applications that use sockets over unregistered third-party TDI transports might stop working after installing this update. Registered TDI transports are not affected. For more information, see Third-party TDI transports might stop working after installing Windows security updates released on or after July 14, 2026.
• [Recycle Bin (known issue)] Fixed: This update addresses an issue where the confirmation dialog might display an internal Recycle Bin file name instead of the original file name when permanently deleting a file. This issue might occur after installing the June 2026 security update (KB5094125).
• [System reliability]
• This update improves system reliability by addressing an issue that could cause Windows to stop responding in certain situations.
• This update improves performance for virtual machines running graphics-intensive applications by resolving a memory leak in the graphics kernel driver. It also reduces excessive memory usage and helps maintain consistent sign-in access.

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

For more information about security vulnerabilities, see the Security Update Guide and the July 2026 Security Updates.

Windows Server 2025 servicing stack update (KB5101372) - 26100.33150​

This update makes quality improvements to the servicing stack, which is the component that installs Windows updates. Servicing stack updates (SSU) ensure that you have a robust and reliable servicing stack so that your devices can receive and install Microsoft updates. To learn more about SSUs, see Simplifying on-premises deployment of servicing stack updates.

Known issues in this update​

Windows Server Update Services (WSUS) does not display error details

After installing KB5070881 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 combines the latest servicing stack update (SSU) for your operating system with the latest cumulative update (LCU). For general information about SSUs, see Servicing stack updates.

Deployment​

If you deploy dynamic updates such as this update to an existing Windows image, ensure the boot.stl file is included as part of the installation media. Failure to include the file might prevent devices from successfully starting from the installation media and can result in error code 0xc0430001.

Note
The boot.stl file is used during Secure Boot validation and must match the Windows version and architecture of the image you are updating.

To ensure the boot.stl file is included as part of the installation media, do one of the following:

• Use the Update WinPE script to update an existing Windows image. (Recommended)
• Manually copy the boot.stl file from the device Windows\Boot\EFI folder to the corresponding folder on your installation media before deploying the update.

For information about how to apply Dynamic Update packages to existing Windows images, see Update Windows installation media with Dynamic Update.

Install this update​

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

File information​

For a list of the files provided in this update, download the file information for cumulative update 5099536.

For a list of the files provided in the servicing stack update, download the file information for the SSU (KB5101372) - version 26100.33150.






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