A guest started with Populated on Demand enabled (PoD) can attempt to reclaim pages which aren't regular guest RAM. This can cause corruption of memory management state in Xen.
Exploitability
AV:NAC:LPR:NUI:NScope
S:UImpact
C:NI:NA:L5.3/CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L