Xen 4.6.x, 4.5.x, 4.4.x, 4.3.x, and earlier do not initialize x86 FPU stack and XMM registers when XSAVE/XRSTOR are not used to manage guest extended register state, which allows local guest domains to obtain sensitive information from other domains via unspecified vectors.
Exploitability
AV:NAC:LPR:NUI:NScope
S:CImpact
C:HI:NA:N8.6/CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N