The x86 emulator in Xen 3.2.x through 4.5.x does not properly ignore segment overrides for instructions with register operands, which allows local guest users to obtain sensitive information, cause a denial of service (memory corruption), or possibly execute arbitrary code via unspecified vectors.
- http://www.oracle.com/technetwork/topics/security/linuxbulletinjan2016-2867209.html
- https://github.com/pigram86/cookbook-xs-maintenance