DeepSeek MCP Server is an MCP server for DeepSeek V4. Starting in version 1.4.2 and prior to version 1.8.0, the self-hosted HTTP transport of "@arikusi/deepseek-mcp-server" exposes "POST /mcp" without any authentication: "createMcpExpressApp" is called without an "authProvider" and no middleware guards the route, so any network-reachable client can issue an unauthenticated "initialize" request and obtain a valid MCP session identifier. In reproduced testing against commit "5e1302171e99", an unauthenticated client was able to initialize a session, enumerate tools, and invoke the local "deepseek_sessions" tool with no credentials. The same unauthenticated session also exposes "deepseek_chat", whose handler uses the server-side "DEEPSEEK_API_KEY" when self-hosted deployments configure one. This issue applies to self-hosted HTTP mode, not the separately documented hosted BYOK endpoint in "README.md", which expects an "Authorization: Bearer ..." header. Upstream self-hosted container assets enable HTTP mode by default ("Dockerfile") and publish port "3000" ("docker-compose.yml"). Version 1.8.0 contains a patch for this issue.