Xen 3.3.x through 4.5.x does not properly restrict access to PCI MSI mask bits, which allows local x86 HVM guest users to cause a denial of service (unexpected interrupt and host crash) via unspecified vectors.
Exploitability
AV:NAC:LAu:NImpact
C:NI:NA:C7.8/AV:N/AC:L/Au:N/C:N/I:N/A:C