Hotfix update (HU) 4 for Microsoft Exchange Server 2019 CU15 was released on September 8, 2025. It includes fixes for non-security issues and may introduces new features. These fixes and features will also be included in later cumulative updates for Exchange Server 2019.
Issues that this hotfix update fixes
Get Cumulative Update 15 HU4 for Exchange Server 2019
Method 1: Windows Update
This update is available through Windows Update. For more information see Windows Update: FAQ.
Method 2: Microsoft Download Center
You can get the standalone update package through the Microsoft Download Center.
- Microsoft Exchange Server 2019 Cumulative Update 15 HU4 -Download the package now
File information
File hash information
| File name | SHA256 hash |
|---|---|
| Exchange2019-KB5066372-x64-en.exe | 718DAC941A608D9EDCDDB6B4D9631417EC446A794D473BBA0CDB1C574DFACA03 |
Hashes for additional languages
The hash tables for additional languages are available here:
- Hash tables for Exchange Server 2019 CU 15 HU4 (KB5066372)- Download the hashes now
Exchange Server file information
The English (United States) version of this update installs files that have the attributes that are listed in the following tables. The dates and times for these files are listed in Coordinated Universal Time (UTC). The dates and times for these files on your local computer are displayed in your local time together with your current daylight-saving time (DST) bias. Additionally, the dates and times may change when you perform certain operations on the files.
- Microsoft Exchange Server 2019 Cumulative Update 15 HU4 -Download the worksheet now
More information
For more information about the deployment of Exchange Server 2019, see Release notes for Exchange Server 2019.
For more information about the coexistence of Exchange Server 2019 and earlier versions of Exchange Server in the same environment, see Exchange Server 2019 system requirements.
For more information about other Exchange updates, see Exchange Server Updates: Build numbers and release dates.
Information about protection and security
Protect yourself online: Windows Security support
Learn how we guard against cyber threats: Microsoft Security
References
Learn about the terminology that Microsoft uses to describe software updates.