Cisco Security Advisory – Cisco IOS Software configured with Authentication Proxy for HTTP(S), Web Authentication or the consent feature, contains a vulnerability that may allow an unauthenticated session to bypass the authentication proxy server or bypass the consent webpage.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/81602/cisco-sa-20090923-auth-proxy.txt
Source: https://packetstormsecurity.com/files/81602/Cisco-Security-Advisory-20090923-auth-proxy.html