An issue was discovered in Xen through 4.9.x allowing x86 PV guest OS users to cause a denial of service (unbounded recursion, stack consumption, and hypervisor crash) or possibly gain privileges via crafted page-table stacking.
Exploitability
AV:LAC:LPR:LUI:NScope
S:CImpact
C:HI:HA:H8.8/CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H