Extended Interior Gateway Routing Protocol (EIGRP) 1.2 as implemented in Cisco IOS after 12.3(2) 12.3(3)B and 12.3(2)T and other products allows remote attackers to cause a denial of service by sending a \spoofed neighbor announcement\ with (1) mismatched k values or (2) \goodbye message\ Type-Length-Value (TLV).