An issue was discovered in Xen through 4.9.x allowing guest OS users to cause a denial of service (host OS crash) or gain host OS privileges by leveraging an incorrect mask for reference-count overflow checking in shadow mode.
Exploitability
AV:LAC:HPR:LUI:NScope
S:CImpact
C:HI:HA:H7.8/CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H