ICMP Router Discovery Protocol (IRDP) is enabled on this host.
IRDP is an extension to the ICMP protocol that allows hosts to discover
routers on their networks by listening for "router advertisement" broadcasts
on their networks. Receipt of router advertisement messages by a host may
result in changes to the host's routing table. Since IRDP does not provide
for the authenticity of router advertisement messages, hosts running IRDP
can be spoofed into changing their routes.
An attacker could send spoofed IRDP router advertisement messages to
the host, causing it to change its default route to whatever the attacker
chooses. This could result either a complete denial-of-service (i.e. changing
the default gateway to something invalid) or susceptibility to passive sniffing
and/or man-in-the-middle attacks (i.e. changing the gateway to a router
under the attacker's control).