In order to meet high availability deployment requirements, Content Services uses Hazelcast, an open-source distributed in-memory object store that supports a wide variety of data structures such as Map, Set, and List. It is important to harden (improve the security) of the cluster because it may expose sensitive data, including user session information, from the application layer to the network layer if the default configuration is not changed.
Note: Hazelcast Community Edition security features are limited, thus the mitigations are mainly related to the network layer plus application layer checks, where Alfresco programmatically permits only to database stored nodes the access to the cluster.