A vulnerability in the implementation of Protected Extensible Authentication Protocol (PEAP) functionality for standalone configurations of Cisco Aironet 1800, 2800, and 3800 Series Access Points could allow an unauthenticated, adjacent malicious user to bypass authentication and connect to an affected device. The vulnerability exists because the affected device uses an incorrect default configuration setting of fail open when running in standalone mode. An attacker could exploit this vulnerability by attempting to connect to an affected device. A successful exploit could allow the malicious user to bypass authentication and connect to the affected device. This vulnerability affects Cisco Aironet 1800, 2800, and 3800 Series Access Points that are running a vulnerable software release and use WLAN configuration settings that include FlexConnect local switching and central authentication with MAC filtering. Cisco Bug IDs: CSCvd46314.