Quick Emulator (Qemu) built with the VirtFS, host directory sharing via Plan 9 File System (9pfs) support, is vulnerable to an improper access control issue. It could occur while accessing files on a shared host directory. 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.
https://security.gentoo.org/glsa/201706-03
https://git.qemu.org/?p=qemu.git%3Ba=commitdiff%3Bh=9c6b899f7a46893ab3b671e341a2234e9c0c060e
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2017-7471