{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "1.4.2"
              },
              {
                "fixed": "1.8.0"
              }
            ],
            "source": [
              "AFFECTED_FIELD",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "1f90faae26935a7c16efaaf7e8251d551efae2c0"
            },
            {
              "fixed": "dab07ed93ddde0ab219d4cb7066785847db53a32"
            }
          ],
          "repo": "https://github.com/arikusi/deepseek-mcp-server",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-72f3-6w86-7rv3"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-306"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55605.json"
  },
  "details": "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.",
  "id": "CVE-2026-55605",
  "modified": "2026-07-15T01:48:58.030706332Z",
  "published": "2026-07-09T21:10:53.882Z",
  "references": [
    {
      "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"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55605.json"
    },
    {
      "type": "ADVISORY",
      "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"
    }
  ],
  "schema_version": "1.8.0",
  "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"
}