Pulse Secure Client 9.0R1 and 5.3RX before 5.3R5, when configured to authenticate VPN users during Windows Logon, can allow attackers to bypass Windows authentication and execute commands on the system with the privileges of Pulse Secure Client. The attacker must interrupt the client's network connectivity, and trigger a connection to a crafted proxy server with an invalid SSL certificate that allows certification-manager access, leading to the ability to browse local files and execute local programs.