Hotfix update (HU) 18 for Microsoft Exchange Server 2016 CU23 was released on September 8, 2025. It includes fixes for non-security issues and may introduce new features. These fixes and features will also be included in later cumulative updates for Exchange Server 2016. ​​​​​​​
Issues that this hotfix update fixes
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​​​​​​​Online archiving fails for on-premises users in hybrid environment
Get Cumulative Update 23 HU18 for Exchange Server 2016
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. Â
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Microsoft Exchange Server 2016Â Cumulative Update 23 HU18 -Download the package now
File information
File hash information
|
File name |
SHA256 hash |
|---|---|
|
Exchange2016-KB5066370-x64-en.exe |
486C145A6D67E6C72AA56C9793C26B3338E7300FACDD59D9FC7BBEDBBF51388A |
Hashes for additional languages
The hash tables for additional languages are available here:
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Hash tables for Exchange Server 2016Â CU 23 HU18 (KB5066370) -Â 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 worksheet. 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.
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Microsoft Exchange Server 2016 Cumulative Update 23 HU18 - Download the worksheet now
More information
For more information about the deployment of Exchange Server 2016, see Release notes for Exchange Server 2016. For more information about the coexistence of Exchange Server 2016 and earlier versions of Exchange Server in the same environment, see Exchange Server 2016 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.
