The PPP parser in tcpdump before 4.9.2 has a buffer over-read in print-ppp.c:handle_mlppp().
https://support.apple.com/HT208221
https://security.gentoo.org/glsa/201709-23
https://github.com/the-tcpdump-group/tcpdump/commit/7335163a6ef82d46ff18f3e6099a157747241629
https://access.redhat.com/errata/RHEA-2018:0705
http://www.tcpdump.org/tcpdump-changes.txt