Cisco 12000 with IOS 12.0 and lines card based on Engine 2 does not properly handle an outbound ACL when an input ACL is not configured on all the interfaces of a multi port line card, which could allow remote attackers to bypass the intended access controls.
http://www.securityfocus.com/bid/3537
http://www.iss.net/security_center/static/7554.php