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).