Exploit code has been released for an actively exploited high severity vulnerability impacting Microsoft Exchange servers. The security bug tracked as CVE-2021-42321 impacts on-premises Exchange Server 2016 and Exchange Server 2019 (including those used by customers in Exchange Hybrid mode) and was patched by Microsoft during November Patch Tuesday. Successful exploitation allows authenticated attackers to execute code remotely on vulnerable Exchange servers.

Source: bleepingcomputer.com