Question : Cisco Discovery Protocol

What are the security issues involved when CDP (Cisco Discovery Protocol)
is enabled on Cisco routers?

Answer : Cisco Discovery Protocol

The risk in having CDP enabled is what a potential attacker could learn about the network. Information as to what model router/switch and what version of the IOS is running is accessible to any system directly connected to a segment that has CDP enabled. Such information may be useful to an attacker in designing an attack on the network. The implementation of the proctocol itself on routers and switches isn't dangerous as it's only an "informational" protcol. Like the danger in having SNMP enabled, it's what an attacker could learn that's dangerous.