"Microsoft has released a new, one-click mitigation tool, Microsoft Exchange On-Premises Mitigation Tool to help customers who do not have dedicated security or IT teams to apply these security updates.We have tested this tool across Exchange Server 2013, 2016, and 2019... This new tool is designed as an interim mitigation for customers who are unfamiliar with the patch/update process or who have not yet applied the on-premises Exchange security update... [The tool] will automatically mitigate CVE-2021-26855 [Microsoft Exchange Server Remote Code Execution Vulnerability] on any Exchange server on which it is deployed..." https://msrc-blog.microsoft.com/202...hange-on-premises-mitigation-tool-march-2021/
