Buffer overflow in the C cli shell in Apache Zookeeper before 3.4.9 and 3.5.x before 3.5.3, when using the "cmd:" batch mode syntax, allows attackers to have unspecified impact via a long command string.

Two four letter word commands "wchp/wchc" are CPU intensive and could cause spike of CPU utilization on Apache ZooKeeper server if abused, which leads to the server unable to serve legitimate client requests. Apache ZooKeeper thru version 3.4.9 and 3.5.2 suffer from this issue, fixed in 3.4.10, 3.5.3, and later.

No authentication/authorization is enforced when a server attempts to join a quorum in Apache ZooKeeper before 3.4.10, and 3.5.0-alpha through 3.5.3-beta. As a result an arbitrary end point could join the cluster and begin propagating counterfeit changes to the leader.

A flaw was found in Apache ZooKeeper. A lack of permission checks while retrieving ACLs allows unsalted hash values to be disclosed for unauthenticated or unprivileged users.