CVE-2005-4437: MD5 Neighbor Authentication in Extended Interior Gateway Routing Protocol (EIGRP) 1.2, as implemented in Ci...

Security readout for executives and security teams

This CVE concerns Cisco IOS EIGRP MD5 neighbor authentication. The reported flaw could let an attacker who can observe routing traffic reuse captured authentication material to disrupt routing behavior, including triggering excessive ARP activity. The main business risk is network availability, not direct data theft. Exposure is most plausible where Cisco IOS 11.3 or later runs EIGRP with MD5 neighbor authentication and untrusted systems can observe or inject routing-plane traffic on the relevant network segment. Treat this as a targeted network availability risk. It deserves prompt validation in EIGRP environments, especially core or branch routing, but the provided evidence does not support emergency treatment for all organizations. Mitigation focus: Check current Cisco guidance for affected IOS trains and recommended corrective action.; Restrict EIGRP adjacency traffic to trusted router links and management domains.; Limit untrusted access to segments carrying routing protocol traffic..

Prepared

Jun 29, 2026, 15:49 UTC (UTC+00:00)

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.