In Microsoft Exchange Server 2019 or Exchange Server 2016, you can assign the "Active Directory Permissions" role to a user, a group, or a role group. The assignment can be limited by using a management scope so that the assignee can only use the permissions granted by this role only on the specific objects within the scope. The assignment can be limited to a specific recipient write scope or configuration write scope. However, even if both recipient and configuration scopes are limited to a narrow scope, there is an easy way for users to hold the "Active Directory Permissions" role to elevate their permissions to the whole Exchange organization.
To fix this issue, install one of the following updates:
For Exchange Server 2019, install the Cumulative Update 5 for Exchange Server 2019 or a later cumulative update for Exchange Server 2019.For Exchange Server 2016, install the Cumulative Update 16 for Exchange Server 2016 or a later cumulative update for Exchange Server 2016.