Qemu emulator <= 3.0.0 built with the NE2000 NIC emulation support is vulnerable to an integer overflow, which could lead to buffer overflow issue. It could occur when receiving packets over the network. A user inside guest could use this flaw to crash the Qemu process resulting in DoS.
https://access.redhat.com/errata/RHSA-2019:2892
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2018-10839
https://lists.debian.org/debian-lts-announce/2018/11/msg00038.html
https://lists.gnu.org/archive/html/qemu-devel/2018-09/msg03273.html
https://usn.ubuntu.com/3826-1/