The remote Debian host is missing a security-related update.
Julien Bernard discovered that libndp, a library for the IPv6 Neighbor Discovery Protocol, does not properly perform input and origin checks during the reception of a NDP message. An attacker in a non-local network could use this flaw to advertise a node as a router, and cause a denial of service attack, or act as a man-in-the-middle.
Upgrade the libndp packages. For the stable distribution (jessie), this problem has been fixed in version 1.4-2+deb8u1.