It was demonstrated that by forging CCP packets, it is possible to "confuse" cluster members about the state of peer members and cause denial of service (cluster members could be forced to incorrectly change their state to "Ready").
Credit: Check Point thanks Christian Port for responsible disclosure of this issue.
Cause
This attack is possible if a malicious user gains Layer 2 access to cluster non-trusted (non-sync) interfaces (whose "Network Objective" in cluster object topology is not "Sync").