The remote Debian host is missing a security-related update.
Several vulnerabilities have been discovered in tcpdump, a command-line network traffic analyzer. These vulnerabilities might result in denial of service or, potentially, execution of arbitrary code.
Upgrade the tcpdump packages. For the oldstable distribution (jessie), these problems have been fixed in version 4.9.2-1~deb8u1. For the stable distribution (stretch), these problems have been fixed in version 4.9.2-1~deb9u1.