Reported October 3, 2001, by Cisco Systems.
Cisco Secure PIX Firewalls using AAA authentication with software 4.0 through 5.3(1)
A vulnerability exists in the Cisco Secure PIX Firewall Authentication that lets a Denial of Service (DoS) condition exist. When a user configures AAA (Authentication, Authorization, Accounting) authentication services on the Cisco Secure PIX Firewall, it's possible for a single-source address to consume all authentication resources, preventing other legitimate users from authenticating. This DoS affects only the authentication resources; other established traffic continues unaffected, and the DoS prevents only new authentication requests.
Discovered by Cisco Systems.