KB5049233 for Exchange Server 2016 and 2019

KB5049233 (November 2024 Exchange SUv2) is the cumulative security update for Exchange Servers 2016 and 2019. It was released on 27 November by the Exchange Server team of Microsoft.

KB5049233 supersedes KB5044062. KB5044062 (November 2024 Exchange SUv1) led to mail delivery issues on Exchange Servers 2016 and 2019 after deployment. Subsequent to the reported issues, Microsoft pulled the Exchange server KB5044062 update from the site.

KB5049233 fixes the transport rules issue on Microsoft Exchange Servers 2019 and 2016. Essentially, KB5049233 replaces the KB5044062 and should be considered as a working-copy of the November security update for Exchange Servers 2019 and 2016.

Salient points about KB5049233 or November Exchange Security Update SUv2

What versions of Exchange can use the KB5049233?

KB5049233 can be installed on the following Exchange versions:

• Microsoft Exchange Server 2019 CU 14
• Microsoft Exchange Server 2019 CU 13
• Microsoft Exchange Server 2016 CU 23

The security update can be downloaded from the Microsoft Catalog site. The links above are from the Microsoft Downloads. Each link corresponds to the corresponding security update for Exchange servers.

Pre-installation Checklist

KB5049233 includes all changes that are part of the KB5044062. You would need to plan installation of KB5049233 based on the action you took when KB5044062 was released.

Here is a quick way to find out the action needed to be undertaken by you.

For administrators who installed KB5044062

If you installed KB5044062 manually, you must install the latest security update KB5049233 manually. This is irrespective of the fact whether you faced issues with transport rules or not.

• If you installed KB5044062 manually, please download and install KB5049233 from the manual links shared above. Remember, download the Exchange security update corresponding to your Exchange server build.

If you installed KB5044062 automatically through Windows Update program, you would need to take either of the two steps shared below.

• If you faced transport rules issue and uninstalled the previous security update, you need to install KB5049233 or the update Exchange Server security update. This would complete securing the Exchange server.

or,

• If you did not face transport rules issue after installing KB5044062 through the Windows Update program, you can skip installation of KB5049233. The December security update of Exchange Server 2019 and 2016 would include changes that are part of the KB5049233. So, installing the December security update would take care of the security update requirements.

If you did not install KB5044062

• If you did not install KB5044062, you must install the updated Exchange security update KB56049233,

1. KB5049233 replaces KB5044062.
2. December security update for Exchange Servers 2019 and 2016 would include all changes that are part of the KB5049233 and KB5044062.
3. As we see it today, you must install KB5049233 for full security of the Exchange servers, given the fact that we are hitting the holidays season. During holidays, hackers are in overdrive mode to target systems and infrastructure.
4. You can skip installing KB5049233 only if you installed KB5044062 and did not run into issues with mail delivery and transport rules.

Reference link:

You may read the Microsoft release notes for KB5049233 here and on this page.