ISC DHCP is vulnerable to integer overflows. A malicious DHCP client with local access could send large amounts of traffic to trigger a reference count overflow on the server side, potentially causing dhcpd to crash.
www.securityfocus.com/bid/103188
www.securitytracker.com/id/1040437
access.redhat.com/errata/RHSA-2018:0469
access.redhat.com/errata/RHSA-2018:0483
access.redhat.com/security/updates/classification/#important
kb.isc.org/article/AA-01565
kb.isc.org/article/AA-01567
kb.isc.org/docs/aa-01567
lists.debian.org/debian-lts-announce/2018/03/msg00015.html
usn.ubuntu.com/3586-1/
usn.ubuntu.com/3586-2/
www.debian.org/security/2018/dsa-4133