Xen 3.3.x through 4.5.x does not properly restrict write access to the host MSI message data field, which allows local x86 HVM guest administrators to cause a denial of service (host interrupt handling confusion) via vectors related to qemu and accessing spanning multiple fields.
Exploitability
AV:LAC:LAu:NImpact
C:NI:NA:C4.9/AV:L/AC:L/Au:N/C:N/I:N/A:C