This security update resolves vulnerabilities in Microsoft Skype for Business Server and Microsoft Lync Server. To learn more about these vulnerabilities, see Microsoft Common Vulnerabilities and Exposures CVE-2021-26422 and Microsoft Common Vulnerabilities and Exposures CVE-2021-26421.

Improvements and fixes

This update also fixes the following issue:

Remote PowerShell cannot be connected after you install update 4470124 for Skype for Business 2019.

How to get and install the update

To get this update, install the following updates:

More information

Security update deployment information

For deployment information about this update, see security update deployment information: May 11, 2021.

How to get help and support for this security update

Protect yourself online: Windows Security support

Learn how we guard against cyber threats: Microsoft Security

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