CVE-2025-59155: Hackmd mcp HackMD MCP Server Has Server-Side Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-g5cg-6c7v-mmpw",
  "modified" : "2025-09-15T20:37:46Z",
  "published" : "2025-09-15T20:37:46Z",
  "aliases" : [ "CVE-2025-59155" ],
  "summary" : "HackMD MCP Server has Server-Side Request Forgery (SSRF) vulnerability",
  "details" : "### Impact\n\nA Server-Side Request Forgery (SSRF) vulnerability that affects all users running the HackMD MCP server in HTTP mode. Attackers could exploit this vulnerability by passing arbitrary `hackmdApiUrl` values through HTTP headers (`Hackmd-Api-Url`) or base64-encoded JSON query parameters. This allows malicious users to:\n\n- Redirect API calls to internal network services\n- Potentially access sensitive internal endpoints\n- Perform network reconnaissance through the server\n- Bypass network access controls\n\nThe vulnerability affects the HTTP transport mode specifically - stdio mode is not impacted as it only accepts requests from stdio.\n\n### Patches\n\nThe vulnerability has been patched in version `1.5.0`. Users should:\n\n1. Update to the latest version of the HackMD MCP server\n2. Set the `ALLOWED_HACKMD_API_URLS` environment variable to restrict allowed HackMD API endpoints\n3. If not set, the server will default to only allowing the official HackMD API URL (`https://api.hackmd.io/v1`)\n\nExample configuration:\n```\nALLOWED_HACKMD_API_URLS=https://api.hackmd.io/v1,https://your-hackmd-instance.com/api/v1\n```\n\n### Workarounds\n\nUsers can mitigate this vulnerability without upgrading by:\n\n1. **Use stdio mode instead of HTTP mode**: Set `TRANSPORT=stdio` or remove the `TRANSPORT` environment variable to disable HTTP mode entirely\n2. **Network-level restrictions**: Use firewall rules or network policies to restrict outbound connections from the server\n3. **Reverse proxy filtering**: Place the MCP server behind a reverse proxy that validates and filters both the `Hackmd-Api-Url` header and the base64-encoded JSON `config` query parameter to prevent malicious `hackmdApiUrl` values\n\n### References\n\n- [OWASP Server-Side Request Forgery Prevention Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/Server_Side_Request_Forgery_Prevention_Cheat_Sheet.html)\n- [HackMD MCP Server Documentation](https://github.com/yuna0x0/hackmd-mcp)",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "hackmd-mcp"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.4.0"
      }, {
        "fixed" : "1.5.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/yuna0x0/hackmd-mcp/security/advisories/GHSA-g5cg-6c7v-mmpw"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2025-59155"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/yuna0x0/hackmd-mcp/commit/43936c78a5bb3dedc74e8f080607a1125caa8c13"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/yuna0x0/hackmd-mcp"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/yuna0x0/hackmd-mcp/releases/tag/v1.5.0"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-918" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2025-09-15T20:37:46Z",
    "nvd_published_at" : "2025-09-15T17:15:36Z"
  }
}