ESX Agent Manager must set the secure flag for cookies.
The secure flag is an option that can be set by the application server when sending a new cookie to the user within an HTTP Response. The purpose of the secure flag is to prevent cookies from being observed by unauthorized parties due to the transmission of a cookie in clear text. By setting the secure flag, the browser will prevent the transmission of a cookie over an unencrypted channel. The ESX Agent Manager is configured to only be accessible over a TLS tunnel, but this cookie flag is still a recommended best practice.