The Definitive Guide to Exchange Server 2019 Cumulative Updates (CUs) & Security Updates (SUs): Downloads & Key Information

The Definitive Guide to Exchange Server 2019 Cumulative Updates (CUs) & Security Updates (SUs): Download Links & Build Numbers

Microsoft Exchange Server 2019 stands as a cornerstone for enterprise communication and collaboration, offering robust email, calendaring, and contact management capabilities. For organizations relying on this powerful on-premises solution, maintaining an up-to-date environment is not merely a recommendation but a critical operational necessity. Regular updates ensure your Exchange 2019 servers are fortified against the latest security vulnerabilities, benefit from new features and performance enhancements, and maintain optimal stability. Neglecting these updates can expose your organization to significant risks, including data breaches, service disruptions, and compliance failures. This comprehensive guide is designed to be your go-to resource for understanding, locating, and managing Cumulative Updates (CUs) and Security Updates (SUs) for Exchange Server 2019. We will delve into the specifics of each update type, provide direct download links or pointers to official Microsoft resources for every CU and SU, list their corresponding build numbers and release dates, and offer essential guidance on keeping your Exchange 2019 infrastructure secure and efficient. Whether you are planning your next update cycle or seeking information on a specific patch, this article aims to provide the clarity and details you need. Need help managing your Exchange 2019 environment or ensuring your update strategy is sound? MedhaCloud offers expert Exchange Server support to assist you every step of the way.

Understanding Updates for Exchange Server 2019

Navigating the update landscape for Exchange Server 2019 requires a clear understanding of the different types of updates Microsoft releases and their implications for your environment. The primary update mechanisms for Exchange 2019 are Cumulative Updates (CUs) and Security Updates (SUs).

Cumulative Updates (CUs): These are the most significant updates for Exchange Server 2019. Unlike the older service pack model, each CU is essentially a full build of Exchange Server. This means that when you install a CU, you are installing the entire Exchange Server 2019 product at that specific CU level, including all previously released CUs and SUs. CUs are typically released on a semi-annual basis and introduce a collection of fixes for issues reported by customers, new features or feature enhancements, and all previously released security patches. Because each CU is a complete installation, you do not need to install previous CUs or the RTM (Release to Manufacturing) version before applying the latest CU. For example, if your server is on CU10 and CU12 is released, you can directly install CU12. It is Microsoft’s strong recommendation to always install the latest available CU to ensure your servers are fully supported and have the most recent non-security and security fixes.

Security Updates (SUs): As the name suggests, Security Updates are released to address specific security vulnerabilities discovered in Exchange Server. These are critical patches and should be applied as promptly as possible according to your organization’s risk assessment and patching policies. SUs are typically released on Microsoft’s Patch Tuesday (the second Tuesday of each month) if new vulnerabilities have been identified and fixed. Unlike CUs, SUs are not full builds of Exchange; instead, they are smaller packages designed to patch specific vulnerabilities on an existing CU level. It is important to note that SUs are CU-specific. This means an SU released for Exchange Server 2019 CU12, for instance, can only be applied to servers already running CU12. If you are on an older CU, you generally need to upgrade to the CU for which the SU is released (or a later CU that includes those security fixes) before you can apply that specific SU, or wait for an SU that is applicable to your current CU if one is provided (though this is less common for very old CUs).

Microsoft’s servicing model for Exchange Server 2019 emphasizes staying current. They typically support the two most recent CUs. Once a new CU is released, support for the N-2 CU (the second-to-last CU before the newly released one) is often phased out after a short period. Therefore, planning regular CU upgrades is essential for maintaining a supported and secure Exchange 2019 environment.

Latest Recommended Update for Exchange Server 2019

To ensure your Exchange Server 2019 environment is maximally protected and running optimally, it is crucial to install the latest available Cumulative Update (CU) and any subsequent Security Updates (SUs). As of our last data compilation (referencing updates up to early 2025), the latest major Cumulative Update is Exchange Server 2019 CU15 (2025H1), released around February 10, 2025. Following this, Hotfix Updates (HUs) or Security Updates (SUs) may have been released for CU15.

For instance, Exchange Server 2019 CU15 Apr25HU (KB5050672), released on April 18, 2025, would be a critical update to apply if you are on CU15.

Key recommendations:

1. Always verify the absolute latest updates directly from the official Microsoft Exchange Server Build Numbers and Release Dates page or the Microsoft Security Update Guide before proceeding with any installation.
2. Prioritize installing the latest available CU for your Exchange Server 2019.
3. After installing the latest CU, ensure all subsequent SUs applicable to that CU are also installed.

For direct access to the download page for Exchange Server 2019 CU15 (KB5042461), you can typically visit the Microsoft Download Center. For the specific Hotfix Update KB5050672, refer to its support article.

Staying vigilant with these updates is paramount for the health and security of your Exchange 2019 deployment.

Comprehensive List of Exchange Server 2019 Cumulative Updates (CUs)

Cumulative Updates (CUs) are full installations of Exchange Server 2019, incorporating all previously released fixes and features. It is always recommended to install the latest available CU. Below is a comprehensive list of CUs for Exchange Server 2019, along with their release dates, build numbers, and links to download pages or Knowledge Base (KB) articles where available. Please note that direct download links for very old CUs might be retired by Microsoft; in such cases, the KB article will provide the most relevant information.

(Note: Build numbers for SUs applied on top of a CU might increment the revision part of the build number. The table primarily lists the base CU build numbers and links to SU KB articles which provide details on specific patched build numbers. Some older CU download links might be retired by Microsoft; always refer to the KB article for the most current status and alternative download paths if available, often through the Microsoft Update Catalog.)

Comprehensive List of Exchange Server 2019 Security Updates (SUs)

Security Updates (SUs) are critical patches released to address vulnerabilities. They are specific to a particular Cumulative Update (CU) version of Exchange Server 2019. The table below lists key SUs. For a complete and up-to-the-minute list of security updates, always consult the Microsoft Security Update Guide and filter for Exchange Server 2019.

Ensuring your Exchange 2019 is patched with the latest SUs is vital for protecting against known exploits. For assistance with developing a robust update strategy and ensuring your servers are secure, explore MedhaCloud Exchange Support solutions. We can help you navigate the complexities of Exchange patching and security.

How to Check Your Current Exchange 2019 Build Number

Knowing the current build number of your Exchange Server 2019 is essential before planning any update. This information tells you which CU and potentially which SUs are already installed. You can easily find this using the Exchange Management Shell (EMS) with one of the following PowerShell commands:

1. To get a detailed version including the AdminDisplayVersion (which usually reflects the CU level):

   powershell Get-ExchangeServer | Format-List Name, Edition, AdminDisplayVersion, ServerRole

   The AdminDisplayVersion will typically show something like Version 15.2 (Build xxx.x), where xxx.x corresponds to a specific CU.

2. To get the precise file version of ExSetup.exe (which is a very accurate way to determine the exact build):

   powershell Get-Command ExSetup.exe | ForEach-Object {$_.FileVersionInfo}

   Look for the ProductVersion or FileVersion field in the output. This long build number (e.g., 15.02.1748.010) can be directly cross-referenced with the build number tables provided in this guide or on Microsoft’s official documentation.

Example Output (for Get-Command ExSetup.exe):

ProductVersion FileVersion      FileName
-------------- -----------      --------
15.2.1748.10   15.02.1748.010 C:\Program Files\Microsoft\Exchange Server\V15\Bin\ExSetup.exe

In this example, 15.2.1748.10 indicates Exchange Server 2019 CU15.

Regularly checking your build numbers against the latest available updates is a key part of Exchange Server administration.

Important Considerations Before Updating Exchange Server 2019

Applying updates to your Exchange Server 2019 environment is a critical task that requires careful planning and execution to minimize risks and ensure a smooth transition. Rushing into an update without proper preparation can lead to unexpected downtime, data corruption, or other serious issues. Here are some vital considerations to address before you begin any CU or SU installation:

1. Thoroughly Read the Release Notes: Before downloading or installing any update, always read the official Microsoft release notes for that specific CU or SU. These documents contain crucial information about prerequisites, known issues, new features, fixes, and any specific instructions or warnings related to the update.
2. Perform Full Backups: This cannot be overstated. Before making any significant changes to your Exchange servers, ensure you have complete, verified backups. This includes:
   • System State backups of your Domain Controllers.
   • Full backups of your Exchange servers, including the operating system and all Exchange databases and transaction logs.
   • Backup of Exchange customizations, such as OWA customizations, web.config files, or any third-party integrations. Verify that your backups are restorable.
3. Test in a Non-Production Environment: If you have a lab or staging environment that mirrors your production setup, always deploy the updates there first. This allows you to identify any potential issues, conflicts with other software, or unexpected behavior in a controlled setting without impacting your live users. Document the process and any challenges encountered.
4. Check Active Directory (AD) Prerequisites:
   • Schema Updates: Some CUs require Active Directory schema extensions. The release notes will specify if PrepareSchema, PrepareAD, and PrepareDomain are necessary. These commands must be run with appropriate permissions (Schema Admins, Enterprise Admins).
   • Forest and Domain Functional Levels: Ensure your AD forest and domain functional levels meet the minimum requirements for the Exchange CU you are installing.
   • AD Health: Run AD health checks (e.g., DCDIAG, REPADMIN) to ensure your domain controllers are healthy and replicating correctly before making schema changes or installing Exchange updates.
5. Verify .NET Framework Compatibility: Exchange Server CUs often have specific .NET Framework version requirements. Ensure the correct version of .NET Framework is installed on all Exchange servers before running the CU setup. Installing a CU with an incompatible .NET Framework version can lead to setup failures or operational problems.
6. Plan for Downtime (if necessary): While SUs can often be installed with minimal downtime (requiring a reboot), CUs are full installations and will require more significant maintenance windows. Communicate planned downtime to users and stakeholders well in advance.
7. Server Order for Updates: In a multi-server environment, especially with Database Availability Groups (DAGs), there is a recommended order for updating servers. Typically, you update Mailbox servers first. Within a DAG, place the member server into maintenance mode before updating. Update non-internet-facing (backend) Mailbox servers before internet-facing (frontend) Mailbox servers if you have such a distinction. Edge Transport servers are generally updated last.
8. Antivirus Exclusions: Ensure your antivirus software is configured with the recommended exclusions for Exchange Server to prevent interference during the update process or with Exchange services post-update.
9. Run Setup as Administrator: Always run the Exchange setup (for CUs or SUs) with elevated privileges (right-click and “Run as administrator”), even if you are logged in as an administrator.
10. Sufficient Disk Space: Ensure there is adequate free disk space on the system drive and the drive where Exchange Server is installed for the setup files and the installation process.
11. Review Third-Party Integrations: If you have third-party applications that integrate with Exchange (e.g., archiving solutions, backup software, monitoring tools, anti-spam products), check their compatibility with the new CU/SU version before updating.

By carefully considering these points, you can significantly reduce the risk of complications and ensure a successful update to your Exchange Server 2019 environment.

General Installation Guidance for Exchange Server 2019 Updates

While this guide does not provide an exhaustive step-by-step tutorial for installing every update (as official Microsoft documentation should always be your primary reference), here is a high-level overview of the general process for installing Cumulative Updates (CUs) and Security Updates (SUs) on Exchange Server 2019.

For Cumulative Updates (CUs):

1. Preparation: Complete all steps outlined in the “Important Considerations Before Updating” section (backups, AD prep, .NET Framework, etc.).
2. Download the CU: Download the correct CU ISO file from the Microsoft Download Center or the link provided in the KB article.
3. Mount the ISO: Mount the ISO image on the Exchange server you intend to update.
4. Prepare Active Directory (if required by the CU):
   • Setup.exe /PrepareSchema /IAcceptExchangeServerLicenseTerms_DiagnosticDataON (Run once per forest from a server in the same AD site as the schema master, by a Schema Admin and Enterprise Admin).
   • Setup.exe /PrepareAD /IAcceptExchangeServerLicenseTerms_DiagnosticDataON (Run once per forest from a server in the same AD site as the schema master, by an Enterprise Admin).
   • Setup.exe /PrepareDomain:<FQDN of domain> /IAcceptExchangeServerLicenseTerms_DiagnosticDataON (Run in each domain containing Exchange servers or mail-enabled users. Can also run /PrepareAllDomains). Wait for AD replication to complete before proceeding.
5. Place Server in Maintenance Mode (especially for DAG members):
   • For DAG members, use scripts like StartDagServerMaintenance.ps1 or manually drain transport queues, set ServerWideOffline, suspend database copies, etc.
6. Run Setup: Navigate to the mounted ISO location in an elevated command prompt or PowerShell and run Setup.exe /Mode:Upgrade /IAcceptExchangeServerLicenseTerms_DiagnosticDataON.
   • Alternatively, you can run Setup.exe directly from the GUI, ensuring it is launched with administrator privileges.
7. Follow Setup Wizard: The wizard will guide you through readiness checks and the upgrade process.
8. Reboot: A reboot is typically required after CU installation.
9. Post-Installation Verification:
   • Check event logs for errors.
   • Verify Exchange services are running.
   • Test mail flow, OWA, ECP, and other critical functionalities.
   • Verify the server build number.
10. Take Server out of Maintenance Mode: For DAG members, use scripts like StopDagServerMaintenance.ps1 or reverse the manual maintenance steps.

For Security Updates (SUs):

1. Preparation: Read release notes, perform backups (though SUs are generally less risky than CUs, backups are still wise).
2. Download the SU: Download the .msp (Microsoft Patch) file from the Microsoft Update Catalog or the link in the KB article.
3. Run as Administrator: Right-click the .msp file and select “Run as administrator.” Alternatively, use an elevated command prompt: msiexec /update <PatchFileName.msp>.
4. Follow Prompts: The installation is usually straightforward.
5. Reboot (if required): Most SUs will require a server reboot to complete the installation.
6. Post-Installation Verification: Check event logs, services, and basic functionality. Verify the build number has been updated as expected per the SU documentation.

Key Official Microsoft Resources for Installation:

• Upgrade Exchange to the latest Cumulative Update: Microsoft Learn
• Install Exchange Security Updates: Refer to the specific KB article for the SU.

Always refer to the latest official Microsoft documentation for the most accurate and detailed installation procedures for any Exchange Server 2019 update.

Troubleshooting Common Exchange 2019 Update Issues (Optional Section)

While thorough preparation can prevent many problems, you might occasionally encounter issues during or after an Exchange Server 2019 update. Here are a few common areas and general troubleshooting approaches:

1. Setup Failures During CU Installation:
   • Readiness Check Failures: Carefully review the errors reported by the readiness checks. They often point to missing prerequisites (like .NET versions, AD preparation steps not completed or replicated, pending reboots, or insufficient permissions).
   • Error Logs: The Exchange Setup log (C:\ExchangeSetupLogs\ExchangeSetup.log) is invaluable. Analyze it for detailed error messages that can pinpoint the cause of the failure.
   • Services Not Starting: If setup completes but services fail to start, check the Application and System event logs for errors related to those services.
2. Issues After SU Installation:
   • OWA/ECP Inaccessibility: This can sometimes happen if the update process didn’t complete correctly or if there are issues with IIS configurations. Running UpdateCas.ps1 and UpdateConfigFiles.ps1 scripts from the Exchange Bin directory, followed by an iisreset, can sometimes resolve these. Check the SU’s KB article for specific post-installation steps or known issues.
   • Repeated Prompts for Update: If an SU seems to install but then reappears as needed, ensure the server was rebooted. Sometimes, manual download and installation from an elevated prompt are more reliable than Windows Update for SUs.
3. Database Mounting Problems (Post-CU):
   • Ensure all servers in a DAG are at the same CU level or within one CU version difference (N and N-1 are supported for coexistence during an upgrade). Mismatched versions can cause database mounting or replication issues.
4. Performance Degradation:
   • Monitor server performance (CPU, memory, disk I/O) after an update. If issues arise, investigate recent changes or consult performance troubleshooting guides for Exchange.
5. Third-Party Application Conflicts:
   • If a third-party application stops working correctly after an Exchange update, check with the vendor for compatibility information or updated versions of their software.

General Troubleshooting Resources:

• Event Viewer: Your first stop for diagnosing issues. Check Application, System, and specific Exchange Server logs.
• Exchange Setup Logs: Located in C:\ExchangeSetupLogs.
• Microsoft Exchange Server Tech Community: A good place to find solutions to common problems or ask questions: Microsoft Tech Community – Exchange
• Official Microsoft Documentation: Search for specific error codes or symptoms on Microsoft Learn.

If you encounter complex issues that you cannot resolve, engaging professional support is recommended. MedhaCloud offers expert troubleshooting and support for Exchange Server 2019. Contact us for assistance.

Conclusion

Keeping your Exchange Server 2019 environment current with the latest Cumulative Updates (CUs) and Security Updates (SUs) is not just a best practice—it’s an essential component of a robust security posture and a well-maintained IT infrastructure. As we’ve detailed, these updates provide critical security patches, bug fixes, and often feature enhancements that ensure the stability, performance, and reliability of your messaging system. By understanding the update types, diligently following pre-installation checks, and adhering to recommended installation procedures, you can significantly minimize risks and ensure smooth update cycles.

This guide has provided a comprehensive overview of Exchange Server 2019 updates, including detailed lists of CUs and SUs with their respective download links and KB articles, methods to check your current build, and important considerations for the update process. We encourage you to use this information as a valuable resource in your Exchange administration tasks.

However, managing Exchange Server, especially in complex environments, can be demanding. If you’re facing challenges with your Exchange Server 2019 updates, planning a migration, or require ongoing expert support to ensure your messaging infrastructure is secure and optimized, MedhaCloud is here to help. Our team of experienced Exchange professionals can provide the assistance you need, from strategic planning to hands-on implementation and troubleshooting. Contact MedhaCloud for expert Exchange support and services today!

We hope this guide empowers you to manage your Exchange Server 2019 updates more effectively. Do you have questions about Exchange 2019 CUs or SUs, or perhaps a tip or experience to share with other administrators? Please share your thoughts and join the discussion in the comments below!

Further Reading in this Series:

• Explore updates for other versions:
• Learn about the latest on-premises offering: