Qemu before version 2.9 is vulnerable to an improper link following when built with the VirtFS. A privileged user inside guest could use this flaw to access host file system beyond the shared folder and potentially escalating their privileges on a host.
Exploitability
AV:AAC:HPR:HUI:NScope
S:CImpact
C:HI:HA:H7.6/CVSS:3.0/AV:A/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:HFile System