The KVM implementation in the Linux kernel through 4.20.5 has a Use-after-Free.
https://usn.ubuntu.com/3932-2/
https://usn.ubuntu.com/3932-1/
https://usn.ubuntu.com/3931-2/
https://usn.ubuntu.com/3931-1/
https://usn.ubuntu.com/3930-2/
https://usn.ubuntu.com/3930-1/
https://support.f5.com/csp/article/K08413011
https://security.netapp.com/advisory/ntap-20190404-0002/
https://lists.debian.org/debian-lts-announce/2019/05/msg00002.html
https://lists.debian.org/debian-lts-announce/2019/04/msg00004.html
https://lists.debian.org/debian-lts-announce/2019/03/msg00034.html
https://github.com/torvalds/linux/commits/master/arch/x86/kvm
https://bugs.chromium.org/p/project-zero/issues/detail?id=1760
https://access.redhat.com/errata/RHSA-2019:4058
https://access.redhat.com/errata/RHSA-2019:3967
https://access.redhat.com/errata/RHSA-2019:0833
https://access.redhat.com/errata/RHSA-2019:0818
https://access.redhat.com/errata/RHBA-2019:0959
http://www.openwall.com/lists/oss-security/2019/02/18/2
http://packetstormsecurity.com/files/151713/KVM-VMX-Preemption-Timer-Use-After-Free.html
http://lists.opensuse.org/opensuse-security-announce/2019-02/msg00042.html