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October 2022 Security Updates for Exchange

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Jaap Wesselius
Microsoft Security Updates for Exchange feature image

On October 11, 2022, Microsoft unexpectedly released new Security Updates (SUs) for Exchange 2013 CU23, Exchange 2016 (CU22 and CU23) and Exchange 2019 (CU11 and CU12).

Exchange CVE-2022-34692, the vulnerabilities addressed in these CUs are the same as addressed by the August 2022 SUs. One thing is that the rating has changed.

Vulnerability Category Severity
CVE-2022-21979 Information disclosure Important
CVE-2022-21980 Elevation of privileges Critical
CVE-2022-24477 Elevation of privileges Critical
CVE-2022-24516 Elevation of privileges Critical
CVE-2022-30134 Elevation of privileges Important

You can download the SUs from the following locations:

Version Download Severity
Exchange 2013 CU23 n/a KB5019076
Exchange 2016 CU22 n/a KB5019077
Exchange 2016 CU23 n/a KB5019077
Exchange 2019 CU11 n/a KB5019077
Exchange 2019 CU12 n/a KB5019077

Please note that these SUs do not address the 0-day exploits of early October. To work around this 0-day, follow the steps as outlined in Michel’s article on this site: October Exchange Zero Day - Everything You Need to Know and Do.

In the August 2022 SUs, Microsoft introduced a feature in Exchange called Windows Extended Protection. Extended protection can help you protect against man in the middle attacks. If you have not enabled extended protection, please do and check the August SU announcement for more details. You can also check my own blog on the August security updates that contain more information regarding the implementation of extended protection.

As always:

  • Security Updates are Cumulative Update specific. You cannot install a security update for CU12 on a CU11 server, be aware of this.
  • Security Updates contain all earlier updates for this specific Cumulative Update.
  • Hybrid Servers need to be updates as well, but if you have decommissioned your last Exchange server and running the Exchange 2019 CU12 management tools for Exchange, then there’s no need to install this update.
  • Before installing into your production environment, please test thoroughly in your test environment.



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Image of Jaap Wesselius
Jaap Wesselius

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Image of Jaap Wesselius
Jaap Wesselius

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