The ESXi Host Client must be configured with a session timeout.

The ESXi Host Client is the UI served up by the host itself, outside of vCenter. It is accessed by browsing to "https://<ESX FQDN>/ui". ESXi is not usually administered via this interface for long periods, and all users will be highly privileged. Implementing a mandatory session idle limit will ensure that orphaned, forgotten, or ignored sessions will be closed promptly.

From the vSphere Client, go to Hosts and Clusters.

Select the ESXi Host >> Configure >> System >> Advanced System Settings.

Select the "UserVars.HostClientSessionTimeout" value and verify it is set to "600".

or

From a PowerCLI command prompt while connected to the ESXi host, run the following command:

Get-VMHost | Get-AdvancedSetting -Name UserVars.HostClientSessionTimeout

If the "UserVars.HostClientSessionTimeout" setting is not set to "600", this is a finding.

From the vSphere Client, go to Hosts and Clusters.

Select the ESXi Host >> Configure >> System >> Advanced System Settings.

Select the "UserVars.HostClientSessionTimeout" value and set it to "600".

or

From a PowerCLI command prompt while connected to the ESXi host, run the following command:

Get-VMHost | Get-AdvancedSetting -Name UserVars.HostClientSessionTimeout | Set-AdvancedSetting -Value "600"