Warpgate is an open source SSH, HTTPS and MySQL bastion host for Linux. Prior to 0.25.6, copy_server_request in warpgate-protocol-http/src/proxy.rs forwards a client-supplied x-warpgate-username header before inject_own_headers appends the authenticated username. Because the request builder preserves repeated values, a proxied backend that trusts the first x-warpgate-username value can authorize an authenticated attacker as another user. The same forwarding policy also accepts the reserved x-warpgate-authentication-type header, and warpgate-common/src/http_headers.rs does not exclude either reserved identity header. This issue is fixed in version 0.25.6.