The ISM module in Cisco IOS on ISR G2 routers does not properly handle authentication-header packets, which allows remote authenticated users to cause a denial of service (module reload) via a series of malformed packets, aka Bug ID CSCub92025.

A vulnerability in the 802.1x multiple-authentication (multi-auth) feature of Cisco IOS Software could allow an unauthenticated, adjacent attacker to bypass the authentication phase on an 802.1x multi-auth port. The vulnerability is due to a logic change error introduced into the code. An attacker could exploit this vulnerability by trying to access an 802.1x multi-auth port after a successful supplicant has authenticated. An exploit could allow the attacker to bypass the 802.1x access controls and obtain access to the network. Cisco Bug IDs: CSCvg69701.