Cisco IOS 12.0 through 12.2, when IP routing is disabled, accepts false ICMP redirect messages, which allows remote attackers to cause a denial of service (network routing modification).
https://exchange.xforce.ibmcloud.com/vulnerabilities/11306
http://www.securityfocus.com/bid/6823
http://securitytracker.com/id?1006075
http://archives.neohapsis.com/archives/bugtraq/2003-02/0131.html