The Cisco HDLC parser in tcpdump before 4.9.2 has a buffer over-read in print-chdlc.c:chdlc_print().
www.debian.org/security/2017/dsa-3971
www.securitytracker.com/id/1039307
www.tcpdump.org/tcpdump-changes.txt
access.redhat.com/errata/RHEA-2018:0705
github.com/the-tcpdump-group/tcpdump/commit/866c60236c41cea1e1654c8a071897292f64be49
github.com/the-tcpdump-group/tcpdump/commit/a1eefe986065846b6c69dbc09afd9fa1a02c4a3d
security.gentoo.org/glsa/201709-23
support.apple.com/HT208221