A vulnerability in 802.1x function of Cisco IOS Software on the Catalyst 6500 Series Switches could allow an unauthenticated, adjacent attacker to access the network prior to authentication. The vulnerability is due to how the 802.1x packets are handled in the process path. An attacker could exploit this vulnerability by attempting to connect to the network on an 802.1x configured port. A successful exploit could allow the attacker to intermittently obtain access to the network.