The qemu implementation in libvirt before 1.3.0 and Xen allows local guest OS users to cause a denial of service (host disk consumption) by writing to stdout or stderr.
http://www.openwall.com/lists/oss-security/2016/05/24/5
http://www.oracle.com/technetwork/topics/security/ovmbulletinjul2016-3090546.html