Psono Server CE && EE versions 0.1.0 through 7.2.3 accepted a user-controlled host when configuring a personal Duo device and passed it to the Duo client without an allowlist or explicit timeout. An authenticated remote attacker could cause the server to connect to selected hosts over HTTPS on port 443 and distinguish failure modes, providing an internal DNS and service-reachability oracle. Connections still required TLS certificate validation, and the flaw did not provide arbitrary protocol or port access. Unresponsive targets could also occupy a server worker until the operating-system timeout.