VMware has published a patch for ESXi 5.1 and the corresponding vCenter Server version.
Product: VMware ESXi 5.1
Release date: May 24, 2016
Patch: ESXi510-201605001
Build: 3872664
Build (security only): 3872638
Links: KB2141429 | Download
VMware vCenter Server 5.1 Update 3d and modules [Release Notes] [Download]
The SSLv3 issue has been addressed in this releases. Support for SSLv3 protocol is enabled by default but is configurable. This removes the risk of an unmanageable ESXi hosts when you update ESXi to the latest version, without having the latest vCenter Server.
To disable SSLv3 in your vSphere environment, you need to update ESXi to ESXi 5.1 build 3872664 released on May 24, 2016 and update vCenter Server to vCenter Server 5.1 Update 3d first and then manually disable SSLv3 through configuration settings, for more information, see KB2139396.
The latest ESXi 5.1.0 Build number is now: 3872664
Updated: ESXi Release and Build Number History
Updated: ESXi Image Profiles