An issue was discovered in Xen through 4.10.x allowing x86 PV guest OS users to cause a denial of service (out-of-bounds zero write and hypervisor crash) via unexpected INT 80 processing, because of an incorrect fix for CVE-2017-5754.
https://xenbits.xen.org/xsa/advisory-259.html
https://www.debian.org/security/2018/dsa-4201
https://security.gentoo.org/glsa/201810-06
https://lists.debian.org/debian-lts-announce/2018/10/msg00009.html