The MCP SSE server started via ToolsMCPServer.run_sse() / launch_tools_mcp_server(transport="sse") binds to 0.0.0.0 by default and builds its Starlette application with no authentication middleware and no Origin-header validation. The module mcp/mcp_security.py provides exactly the needed controls (origin validation, DNS-rebinding detection, auth-header enforcement, a SecurityConfig), but none of these functions are ever called by any transport — they are dead code. Any host that can reach the port can list and invoke every registered tool with no credentials, and a victim's browser can drive the same calls against a localhost instance via DNS rebinding.

Affected code: src/praisonai-agents/praisonaiagents/mcp/mcp_server.py

• run_sse defaults host to all interfaces (line 245) and builds the app with only debug and routes
  • no middleware= and no per-route auth/origin gate (lines ~271-289): app = Starlette(debug=self._debug, routes=[ Route(sse_path, endpoint=handle_sse), # "/sse" Mount(messages_path, app=sse_transport.handle_post_message), # "/messages/" ]) uvicorn.run(app, host=host, port=port)
• launch_tools_mcp_server also defaults host="0.0.0.0" (line 301).

src/praisonai-agents/praisonaiagents/mcp/mcp_security.py defines but the transports never call:

• is_valid_origin (line 30), is_potential_dns_rebinding (line 110), validate_auth_header (line 167), SecurityConfig.is_origin_allowed (line 236). These symbols are referenced only inside mcp_security.py and the init re-export. (mcp_websocket.py's auth references are CLIENT-side, not server validation.)

Impact: launch_tools_mcp_server(transport="sse") is the documented path for exposing tools over MCP. With the defaults above it is an unauthenticated, network-reachable tool-execution endpoint. Blast radius equals the capabilities of the registered tools; with file/shell/code-exec tools this is RCE. With no Origin check, a malicious page the victim merely visits can rebind its hostname to 127.0.0.1 and issue the JSON-RPC calls cross-origin against a developer's local server.

Proof of concept: Static proof (AST analysis of unmodified source): Check 1 - run_sse(host='0.0.0.0'); launch_tools_mcp_server(host='0.0.0.0') -> EXPOSED Check 2 - Starlette(...) kwargs: ['debug','routes'] -> NO middleware= (no auth/origin gate) Check 3 - is_valid_origin / is_potential_dns_rebinding / validate_auth_header / SecurityConfig never called by any transport -> DEAD CODE Live exploitation against a running server: curl -N http://VICTIM:8080/sse

event: endpoint / data: /messages/?session_id=<sid>

curl -X POST "http://VICTIM:8080/messages/?session_id=<sid>" -H 'Content-Type: application/json' -d '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2024-11-05", "capabilities":{},"clientInfo":{"name":"x","version":"1"}}}' curl -X POST "<sid>" -H 'Content-Type: application/json' -d '{"jsonrpc":"2.0","id":2,"method":"tools/call","params":{"name":"<tool>","arguments":{...}}}' No Authorization header anywhere. Browser DNS-rebinding variant drives the same calls cross-origin.