@arikusi/deepseek-mcp-server: Missing Authentication on Self-Hosted HTTP MCP Endpoint

Summary

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).

Affected Code

src/transport-http.ts:17 — createMcpExpressApp called without authProvider; no challenge is issued to incoming requests

export function createHttpApp(serverFactory: () => McpServer) {
  const app = createMcpExpressApp({ host: '0.0.0.0' });

src/transport-http.ts:31 — POST /mcp handler instantiates a full MCP session for any body that satisfies isInitializeRequest, with no preceding auth check

  app.post('/mcp', async (req, res) => {
    const sessionId = req.headers['mcp-session-id'] as string | undefined;

    if (sessionId && transports[sessionId]) {
      await transports[sessionId].handleRequest(req, res, req.body);
      return;
    }

    if (!sessionId && isInitializeRequest(req.body)) {
      const transport = new StreamableHTTPServerTransport({
        sessionIdGenerator: () => randomUUID(),
        onsessioninitialized: (id) => {
          transports[id] = transport;
          console.error(`[DeepSeek MCP] HTTP session initialized: ${id}`);
        },
      });

      const server = serverFactory();
      await server.connect(transport);
      await transport.handleRequest(req, res, req.body);