You might be aware of the 3 critical security issues that VMware has published and fixed a couple of days ago in VMSA-2015-0007. The information provided in the security advisory regarding the first issue, CVE-2015-5177 (ESXi OpenSLP Remote Code Execution), are:
VMware ESXi contains a double free flaw in OpenSLP's SLPDProcessMessage() function. Exploitation of this issue may allow an unauthenticated attacker to remotely execute code on the ESXi host.
VMware ESXi 5.5 without patch ESXi550-201509101
VMware ESXi 5.1 without patch ESXi510-201510101
VMware ESXi 5.0 without patch ESXi500-201510101
In this post I am trying to give a better understanding of the vulnerability and its consequences. Please note that the information in this post are my personal opinions. I cannot guarantee that these information are accurate. The main fact is that VMware has published a fix and you should install the patch to be on the safe side. In the real world, you might have something like a "change process" where you can't rollout the patch for hundreds of systems immediately. Or you have a single ESXi that you don't want to reboot at the moment. In this situation, this post tries to help...