The vSphere Client (HTML5) contains a vulnerability in a vSphere authentication mechanism for the Virtual SAN Health Check, Site Recovery, vSphere Lifecycle Manager, and VMware Cloud Director Availability plug-ins. A malicious actor with network access to port 443 on vCenter Server may perform actions allowed by the impacted plug-ins without authentication.
http://packetstormsecurity.com/files/162812/VMware-Security-Advisory-2021-0010.html
https://www.vmware.com/security/advisories/VMSA-2021-0010.html