Buffer over-read in print-isoclns.c:isis_print() in IS-IS parser was found. This vulnerability can be exploited in two ways. The first is to produce a .pcap file with crafted packet(s) for the protocol(s) concerned and make the target system try to decode the file using tcpdump. The second is to send specially crafted packet(s) to the network segment where the target system is running a tcpdump process that is decoding a live packet capture. In the latter case it depends on the specific network protocol if the crafted packet(s) may be sent from the local segment only or from a remote Internet host.
Acknowledgments: Name: the Tcpdump project
This issue was addressed in Red Hat Enterprise Linux 7 via RHEA-2018:0705, which rebased tcpdump to 4.9.2: https://access.redhat.com/errata/RHEA-2018:0705