TrustTunnel is an open-source VPN protocol with a server-side request forgery and and private network restriction bypass in versions prior to 0.9.114. In tcp_forwarder.rs, SSRF protection for allow_private_network_connections = false was only applied in the TcpDestination::HostName(peer) path. The TcpDestination::Address(peer) => peer path proceeded to TcpStream::connect() without equivalent checks (for example is_global_ip, is_loopback), allowing loopback/private targets to be reached by supplying a numeric IP. The vulnerability is fixed in version 0.9.114.
Weakness
The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.