A security issue was discovered in pcs project. It is caused by incorrect permissions on a unix socket used for internal communication between pcs daemons. A privilege escalation could happen by obtaining authentication token for hacluster user. With the hacluster token, an attacker has complete control over the cluster managed by pcs. The bug was introduced in pcs version 0.10.5 by this bz [1]
[1] https://bugzilla.redhat.com/showbug.cgi?id=1783106