interface_release_resource in hw/display/qxl.c in QEMU 3.1.x through 4.0.0 has a NULL pointer dereference.
http://lists.opensuse.org/opensuse-security-announce/2019-09/msg00000.html
http://lists.opensuse.org/opensuse-security-announce/2019-09/msg00008.html
https://access.redhat.com/errata/RHBA-2019:3723
https://access.redhat.com/errata/RHSA-2019:2607
https://access.redhat.com/errata/RHSA-2019:2892
https://access.redhat.com/errata/RHSA-2019:3179
https://access.redhat.com/errata/RHSA-2019:3345
https://access.redhat.com/errata/RHSA-2019:3742
https://access.redhat.com/errata/RHSA-2019:3787
https://access.redhat.com/errata/RHSA-2019:4344
https://lists.debian.org/debian-lts-announce/2019/09/msg00021.html
https://lists.gnu.org/archive/html/qemu-devel/2019-05/msg01321.html
https://seclists.org/bugtraq/2019/May/76
https://usn.ubuntu.com/4191-1/
https://usn.ubuntu.com/4191-2/