Langflow is a tool for building and deploying AI-powered agents and workflows. Prior to 1.9.0, Langflow's /api/v1/monitor router exposes 7 endpoints that perform read, write, and delete operations on user-owned resources — messages, sessions, build artifacts, and LLM transaction logs — without verifying that the authenticated requester owns the targeted resource. Any authenticated user can read, modify, rename, or permanently delete another user's data by supplying the target's resource ID or flow_id. This is a classic IDOR/BOLA vulnerability. Notably, the same source file (monitor.py) contains one correctly-implemented endpoint that uses an ownership check, demonstrating the correct pattern was known but inconsistently applied. This vulnerability is fixed in 1.9.0.

Affected: PyPI: langflow

### Summary

Langflow's `/api/v1/monitor` router exposes 7 endpoints that perform read, write, and delete operations on user-owned resources — messages, sessions, build artifacts, and LLM transaction logs — without verifying that the authenticated requester owns the targeted resource. Any authenticated user can read, modify, rename, or permanently delete another user's data by supplying the target's resource ID or `flow_id`. This is a classic IDOR/BOLA vulnerability. Notably, the same source file (`monitor.py`) contains one correctly-implemented endpoint that uses an ownership check, demonstrating the correct pattern was known but inconsistently applied.

### Details

**Source file: `src/backend/base/langflow/api/v1/monitor.py`**

The correct pattern (used only in `GET /monitor/messages`, lines 77–80): ```python stmt = select(MessageTable) stmt = stmt.join(Flow, MessageTable.flow_id == Flow.id) stmt = stmt.where(Flow.user_id == current_user.id) # ownership enforced ```

All 7 vulnerable endpoints are missing this guard:

**1. `GET /api/v1/monitor/builds` (lines 27–33)** — reads build data for any `flow_id`: ```python @router.get("/builds", dependencies=[Depends(get_current_active_user)]) async def get_vertex_builds(flow_id: Annotated[UUID, Query()], session: DbSession): vertex_builds = await get_vertex_builds_by_flow_id(session, flow_id) # no ownership check return VertexBuildMapModel.from_list_of_dicts(vertex_builds) ```

**2. `DELETE /api/v1/monitor/messages` (l…

Affected: PyPI: langflow

Langflow is a tool for building and deploying AI-powered agents and workflows. Prior to 1.9.0, Langflow's /api/v1/monitor router exposes 7 endpoints that perform read, write, and delete operations on user-owned resources — messages, sessions, build artifacts, and LLM transaction logs — without verifying that the authenticated requester owns the targeted resource. Any authenticated user can read, modify, rename, or permanently delete another user's data by supplying the target's resource ID or flow_id. This is a classic IDOR/BOLA vulnerability. Notably, the same source file (monitor.py) contains one correctly-implemented endpoint that uses an ownership check, demonstrating the correct pattern was known but inconsistently applied. This vulnerability is fixed in 1.9.0.

Ein Angreifer kann mehrere Schwachstellen in Langflow ausnutzen, um Sicherheitsvorkehrungen zu umgehen, Daten zu manipulieren und vertrauliche Informationen offenzulegen.