{"id":"CVE-2026-61647","aliases":["GHSA-jjhp-8crj-mppq"],"url":"https://o3.security/vulnerability/CVE-2026-61647","summary":"@roomi-fields/notebooklm-mcp has 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.","published":"2026-09-21T21:00:58.673Z","modified":"2026-10-21T02:58:52.521924927Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"npm","name":"@roomi-fields/notebooklm-mcp","fixedVersion":"2.0.3"}],"fix":{"url":"https://github.com/roomi-fields/notebooklm-mcp/commit/13828d9ff3933839ce14c1797d3b20a6bb7694a6","label":"roomi-fields/notebooklm-mcp@13828d9"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/61xxx/CVE-2026-61647.json"},{"type":"ADVISORY","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"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-21T02:58:52.521924927Z"}}