Qemu is vulnerable to privilege escalation. An improper link following occurs when building with the VirtFS. A privileged user inside guest can exploit the vulnerability to access host file system beyond the shared folder and potentially escalating their privileges on a host.
www.openwall.com/lists/oss-security/2017/01/17/12
www.securityfocus.com/bid/95461
www.securitytracker.com/id/1037604
bugzilla.redhat.com/show_bug.cgi?id=CVE-2016-9602
lists.debian.org/debian-lts-announce/2018/09/msg00007.html
lists.gnu.org/archive/html/qemu-devel/2017-01/msg06225.html
lists.gnu.org/archive/html/qemu-devel/2017-02/msg04347.html
security.gentoo.org/glsa/201704-01