Exchange Server Cumulative Update CU 14 (February 13, 2024)

Exchange Logo[German]Microsoft has released the cumulative update CU 2024 H1 for Exchange Server 2019 on February 13, 2024. This update (CU 14) contains fixes for customer-reported issues, a security change and all previously released security updates (SUs).


I came across the following tweet from the Exchange team on Twitter about the update CU 2024 H1 (CU 14) for Exchange Server 2019. In addition, a reader pointed out the update to me by email (thanks for that). Microsoft has published the Techcommunity article Released: 2024 H1 Cumulative Update for Exchange Server with a description of the update.

Exchange Server 2019 CU 14

In the meantime, only Exchange Server 2019 is still in support (for CUs) and will receive the penultimate CU (see Exchange Server 2019 Mainstream Support ended on January 9, 2024 – but has few consequences). The Cumulative Update (CU) 2024 H1 for Exchange Server 2019 (CU14) contains fixes for issues reported by customers, a security change and all previously released security updates (SUs).

Exchange Server 2019 Cumulative Update 14 (KB5035606), VLSC Download, Download

The update closes the critical vulnerability CVE-2024-21410 described in Microsoft Security Update Summary (February 13, 2024), if the Extended Protection (EP) is enabled by default. See also Microsoft Exchange Server Elevation of Privilege Vulnerability CVE-2024-21410 for the vulnerability. A full list of fixes is included in the KB article for CU14, but we would also like to highlight some changes in this CU. CU 14 also introduces some changes.

Changes and new features in CU 14

The cumulative update (CU) 2024 H1 (CU14) introduces a number of changes to Exchange Server 2019.


Extended Protection activated by default

It was already announced in August 2023: As of CU14, Setup activates the Windows Extended Protection (EP) feature on the Exchange server to be installed by default. This happens when administrators run the GUI version of Setup and when they run the command line version of Setup without using the Setup switch /DoNotEnableEP or /DoNotEnableEPFEEWS to disable the activation. See the EP setup documentation for more information.

Although Setup enables EP by default, it does not check if your organization is ready or able to use EP. Details can be found in the Techcommunity article.

Support for .NET Framework 4.8.1 on Windows Server 2022

CU14 also introduces support for .NET Framework 4.8.1. However, this only applies to Exchange 2019 versions installed on Windows Server 2022 (cannot be installed on older versions). The support matrix for Exchange Server has been updated to reflect this change.

TLS 1.3 support moved to CU15

It was originally announced that CU14 would bring TLS 1.3 to Windows Server 2022. However, this is not the case and has been postponed to CU15. Microsoft's developers are still testing and validating TLS 1.3 with Exchange Server and did not want to delay the release of CU14. Support for TLS 1.3 will be released in CU15 later this year.

The Techcommunity articl Released: 2024 H1 Cumulative Update for Exchange Server contains some more information on the vulnerability CVE-2024-21410. Various questions in connection with the update installation are discussed in the comments.

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Exchange Server Cumulative Update CU 14 (February 13, 2024)

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