Another year, another Patch Tuesday! A quick blog on January 2022’s security updates for Exchange Server 2013 up to 2019.

The vulnerabilities addressed in these security updates are:

Vulnerability	Category	Severity	Rating
CVE-2022-21969	Remote Code Execution	Important	CVSS:3.1 9.0 / 7.8
CVE-2022-21855	Remote Code Execution	Important	CVSS:3.1 9.0 / 7.8
CVE-2022-21846	Remote Code Execution	Critical	CVSS:3.0 9.0 / 7.8

Vulnerabilities mentioned in the table above are addressed in the following security updates.

Exchange	Download	Build	KB	Supersedes
Exchange 2019 CU11	Download	15.2.986.15	KB5008631	KB5007409
Exchange 2019 CU10	Download	15.2.922.20	KB5008631	KB5007409
Exchange 2016 CU22	Download	15.1.2375.18	KB5008631	KB5007409
Exchange 2016 CU21	Download	15.1.2308.21	KB5008631	KB5007409
Exchange 2013 CU23	Download	15.0.1497.28	KB5008631	KB5007409

More detailed information can be found at the original blog post here. The security update also fixes the OWA redirection problem for Exchange hybrid deployments introduced with the November security updates.

Be advised that these security updates are Cumulative Update level specific. You cannot apply the update for Exchange 2019 CU11 to Exchange 2019 CU10. Also, the security update download has the same name for different Cumulative Updates, and I would suggest tagging the file name with the CU level, e.g. Exchange2019-CU10-KBXXXXXX-x64-en.msp.

As a reminder, run the Security Update from an elevated command prompt to prevent issues during installation. In other words: Do not just double-click on the .MSP file. And on a final note, as with any patch or update, I’d recommend to apply this in a test environment first, prior to implementing it in production. However, it is not recommended to wait for regular maintenance cycles when it concerns security updates, and follow a more agile approach; the ratings are an indication of the urgency.