vpxd in VMware vCenter Server 5.0 before u3e, 5.1 before u3, and 5.5 before u2 allows remote attackers to cause a denial of service via a long heartbeat message.
http://www.securityfocus.com/bid/76932
http://www.securitytracker.com/id/1033720
http://www.vmware.com/security/advisories/VMSA-2015-0007.html