CVE-2018-3825
In Elastic Cloud Enterprise (ECE) versions prior to 1.1.4 a default master encryption key is used in the process of granting ZooKeeper access to Elasticsearch clusters. Unless explicitly overwritten, this master key is predictable across all ECE deployments. If an attacker can connect to ZooKeeper directly they would be able to access configuration information of other tenants if their cluster ID is known.
Source: CVE-2018-3825