CVE-2025-68478: Langflow External Control Of File Name Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-f43r-cc68-gpx4",
  "modified" : "2026-06-06T00:36:53Z",
  "published" : "2025-12-19T22:53:13Z",
  "aliases" : [ "CVE-2025-68478" ],
  "summary" : "External Control of File Name or Path in Langflow",
  "details" : "**Vulnerability Overview**\n\nIf an arbitrary path is specified in the request body's `fs_path`, the server serializes the Flow object into JSON and creates/overwrites a file at that path. There is no path restriction, normalization, or allowed directory enforcement, so absolute paths (e.g., /etc/poc.txt) are interpreted as is.\n\n**Vulnerable Code**\n\n1. It receives the request body (flow), updates the DB, and then passes it to the file-writing sink.\n    \n    https://github.com/langflow-ai/langflow/blob/ac6e2d2eabeee28085f2739d79f7ce4205ca082c/src/backend/base/langflow/api/v1/flows.py#L154-L168\n    \n    ```python\n    @router.post(\"/\", response_model=FlowRead, status_code=201)\n    async def create_flow(\n        *,\n        session: DbSession,\n        flow: FlowCreate,\n        current_user: CurrentActiveUser,\n    ):\n        try:\n            db_flow = await _new_flow(session=session, flow=flow, user_id=current_user.id)\n            await session.commit()\n            await session.refresh(db_flow)\n    \n            await _save_flow_to_fs(db_flow)\n    \n        except Exception as e:\n    ```\n    \n2. Applies authentication dependency (requires API Key/JWT) when accessing the endpoint.\n    \n    https://github.com/langflow-ai/langflow/blob/ac6e2d2eabeee28085f2739d79f7ce4205ca082c/src/backend/base/langflow/api/utils/core.py#L36-L38\n    \n    ```python\n    CurrentActiveUser = Annotated[User, Depends(get_current_active_user)]\n    CurrentActiveMCPUser = Annotated[User, Depends(get_current_active_user_mcp)]\n    DbSession = Annotated[AsyncSession, Depends(get_session)]\n    ```\n    \n3. The client can directly specify the save path, including `fs_path`.\n    \n    https://github.com/langflow-ai/langflow/blob/ac6e2d2eabeee28085f2739d79f7ce4205ca082c/src/backend/base/langflow/api/v1/flows.py#L66-L70\n    \n    ```python\n    ):\n        try:\n            await _verify_fs_path(flow.fs_path)\n    \n            \"\"\"Create a new flow.\"\"\"\n    ```\n    \n4. It attempts to create the file (or *the* file, in the case of a path without a parent) directly without path validation.\n    \n    https://github.com/langflow-ai/langflow/blob/ac6e2d2eabeee28085f2739d79f7ce4205ca082c/src/backend/base/langflow/api/v1/flows.py#L45-L49\n    \n    ```python\n    async def _verify_fs_path(path: str | None) -> None:\n        if path:\n            path_ = Path(path)\n            if not await path_.exists():\n                await path_.touch()\n    ```\n    \n5. Serializes the Flow object to JSON and writes it to the specified path in \"w\" mode (overwriting).\n    \n    https://github.com/langflow-ai/langflow/blob/ac6e2d2eabeee28085f2739d79f7ce4205ca082c/src/backend/base/langflow/api/v1/flows.py#L52-L58\n    \n    ```python\n    async def _save_flow_to_fs(flow: Flow) -> None:\n        if flow.fs_path:\n            async with async_open(flow.fs_path, \"w\") as f:\n                try:\n                    await f.write(flow.model_dump_json())\n                except OSError:\n                    await logger.aexception(\"Failed to write flow %s to path %s\", flow.name, flow.fs_path)\n    ```\n    \n\n**PoC Description**\n\nWhen an authenticated user passes an arbitrary path in `fs_path`, the Flow JSON is written to that path. Since `/tmp` is usually writable, it is easy to reproduce. In a production environment, writing to system-protected directories may fail depending on permissions.\n\n**PoC**\n\n- **Before Exploit**\n   \n\n    <img width=\"1918\" height=\"658\" alt=\"image\" src=\"https://github.com/user-attachments/assets/fe3c2306-091d-4cb0-b4dc-c7fb63c03d8d\" />\n    \n- **After Exploit**\n    \n    ```bash\n    curl -sS -X POST \"http://localhost:7860/api/v1/flows/\" \\\n      -H \"Content-Type: application/json\" \\\n      -H \"x-api-key: sk-8Kyzf9IQ-UEJ_OtSTaJq4eniMT9_JKgZ7__q8PNkoxc\" \\\n      -d '{\"name\":\"poc-etc\",\"data\":{\"nodes\":[],\"edges\":[]},\"fs_path\":\"/tmp/POC.txt\"}'\n    ```\n    \n    <img width=\"1918\" height=\"742\" alt=\"image\" src=\"https://github.com/user-attachments/assets/cc0b0c96-1c2d-4d56-b558-5ba97e0ec174\" />\n    \n\n### Impact\n\n- **Authenticated Arbitrary File Write (within server permission scope):** Risk of corrupting configuration/log/task files, disrupting application behavior, and tampering with files read by other components.\n- **Both absolute and relative paths are allowed, enabling base directory traversal.** The risk of overwriting system files increases in environments with root privileges or weak mount/permission settings.\n- **The file content is limited to Flow JSON,** but the impact is severe if the target file is parsed by a JSON parser or is subject to subsequent processing.\n- **In production environments, it is essential to enforce a save root, normalize paths, block symlink traversal, and minimize permissions.**",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "langflow"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.7.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/langflow-ai/langflow/security/advisories/GHSA-f43r-cc68-gpx4"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2025-68478"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/langflow-ai/langflow"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pypa/advisory-database/tree/main/vulns/langflow/PYSEC-2025-125.yaml"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-610", "CWE-73" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2025-12-19T22:53:13Z",
    "nvd_published_at" : "2025-12-19T18:15:51Z"
  }
}