Buffer overflow in the legacy Datum Programmable Time Server (DPTS) refclock driver in NTP before 4.2.8p10 and 4.3.x before 4.3.94 allows local users to have unspecified impact via a crafted /dev/datum device.
https://usn.ubuntu.com/3707-2/
https://security.FreeBSD.org/advisories/FreeBSD-SA-17:03.ntp.asc
https://access.redhat.com/errata/RHSA-2018:0855
https://access.redhat.com/errata/RHSA-2017:3071