Citrix is aware of the recent vulnerability that has been reported against the Xen hypervisor. This issue is known as the 'VENOM' vulnerability and has been assigned the following CVE number:
CVE-2015-3456: http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-3456
The following sections will provide guidance to customers on the potential impact of this issue. Citrix is actively analysing the impact of this vulnerability on supported versions of Citrix XenServer. Additional details and guidance will be added to this document as soon as they are available.