Squid before 4.4, when SNMP is enabled, allows a denial of service (Memory Leak) via an SNMP packet.
www.squid-cache.org/Advisories/SQUID-2018_5.txt
www.squid-cache.org/Versions/v5/changesets/squid-5-644131ff1e00c1895d77561f561d29c104ba6b11.patch
github.com/squid-cache/squid/pull/313
lists.debian.org/debian-lts-announce/2018/11/msg00032.html
lists.debian.org/debian-lts-announce/2020/07/msg00009.html
usn.ubuntu.com/4059-1/