CVE-2026-61647: @roomi fields/notebooklm mcp Path Traversal Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-jjhp-8crj-mppq",
  "modified" : "2026-09-22T14:43:26Z",
  "published" : "2026-09-22T14:43:26Z",
  "aliases" : [ "CVE-2026-61647" ],
  "summary" : "@roomi-fields/notebooklm-mcp has a path traversal in vault.batch tool that allows arbitrary file write outside intended vault directory",
  "details" : "## Summary\n\nThe `vault_batch` MCP tool (and the equivalent `POST /batch-to-vault` HTTP endpoint) accepted a caller-supplied `vault_dir` path that was passed directly to `path.resolve()` + `fs.mkdir()` with no containment check. A caller — or a prompt-injected LLM driving the MCP — could therefore create directories and write `.md` / `.json` answer files anywhere the server process can write.\n\nThe `slug_prefix` parameter had a parallel, smaller traversal vector: it was concatenated into the filename without sanitization, so a prefix containing `/` or `..` could escape the resolved vault directory through the filename component.\n\n## Impact\n\nFile write (markdown + JSON sidecars) to any location writable by the server process. The written files are inert content (no code execution by themselves), but in a multi-user context — or when the MCP server is driven by an LLM that has read untrusted content (prompt injection) — this allows an attacker to plant files in sensitive locations (autostart folders, shell startup files, etc.) for downstream exploitation.\n\nThe vulnerability exists from **v1.6.0** (when the HTTP `/batch-to-vault` endpoint was introduced) and v1.7.0 (when the same logic was exposed as the `batch_to_vault` MCP tool) through **v2.0.2**.\n\n## Patch\n\nFixed in **v2.0.3**:\n\n- **Opt-in containment via `NOTEBOOKLM_VAULT_ROOT` env var.** When set, `vault_dir` is resolved relative to that root and `realpath`-based containment is enforced. Absolute paths or `..` segments outside the root are rejected with a clear error.\n- **`slug_prefix` is always sanitized.** Path separators (`/`, `\\`), `..` sequences and NUL bytes are stripped, length capped at 64 characters. This applies regardless of whether `NOTEBOOKLM_VAULT_ROOT` is set.\n- 15 unit tests in `src/__tests__/vault-writer.test.ts` cover the escape vectors (absolute paths, sibling-prefix attacks, `..` traversal, NUL/separator stripping).\n\n## Workarounds for users who cannot upgrade\n\n- Run the MCP server under a dedicated unprivileged user with write access only to the intended vault directory.\n- Do not expose the HTTP `/batch-to-vault` endpoint beyond localhost.\n- If using an LLM that ingests untrusted content, validate any `vault_dir` arguments before forwarding them to the MCP.\n\n## Configuration requirement after upgrade (important)\n\nv2.0.3 preserves the legacy unrestricted behaviour when `NOTEBOOKLM_VAULT_ROOT` is **unset**, to keep existing single-user local setups working. **To enable containment, set `NOTEBOOKLM_VAULT_ROOT` in the server environment** to a directory that should bound all vault writes.\n\n## Credit\n\nReported by @mcfly-zzh — thanks for the careful diagnosis and follow-up verification.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@roomi-fields/notebooklm-mcp"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.6.0"
      }, {
        "fixed" : "2.0.3"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/roomi-fields/notebooklm-mcp/security/advisories/GHSA-jjhp-8crj-mppq"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-61647"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/roomi-fields/notebooklm-mcp/issues/15"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/roomi-fields/notebooklm-mcp/commit/13828d9ff3933839ce14c1797d3b20a6bb7694a6"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/roomi-fields/notebooklm-mcp"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/roomi-fields/notebooklm-mcp/releases/tag/v2.0.3"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-22", "CWE-73" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-09-22T14:43:26Z",
    "nvd_published_at" : "2026-09-21T21:17:07Z"
  }
}