It was found that _set_key in agent/helpers/table_container.c in Net-SNMP before 5.8 has a NULL Pointer Exception bug that can be used by an authenticated attacker to remotely cause the instance to crash via a crafted UDP packet, resulting in Denial of Service.
Created net-snmp tracking bugs for this issue:
Affects: fedora-all [bug 1637573]
Unable to reproduce on any version of RHEL using instructions. This appears to be a duplicate of CVE-2015-5621. See the reference page for those details. "Update: "vuln1" was assigned CVE-2015-5621 (see references), therefore CVE-2018-18066 has been marked as duplicate."
This looks to have been patched in RHEL6 and RHEL7 at least via https://bugzilla.redhat.com/show_bug.cgi?id=1212408. I expected that it would trigger on RHEL5 at least, but it does not.
More notes about duplicate CVE: