PYSEC-2026-1524

Summary

Multiple critical API endpoints in Langflow are missing authentication controls, allowing any unauthenticated user to access sensitive user conversation data, transaction histories, and perform destructive operations including message deletion. This affects endpoints handling personal data and system operations that should require proper authorization.

Details

The vulnerability exists in three API endpoints within src/backend/base/langflow/api/v1/monitor.py that are missing the required dependencies=[Depends(get_current_active_user)] authentication dependency:

Affected Endpoints:

1. GET /api/v1/monitor/messages (Line 61)

   @router.get("/messages")  # ❌ Missing authentication
   async def get_messages(
       session: DbSession,
       flow_id: Annotated[UUID | None, Query()] = None,
       session_id: Annotated[str | None, Query()] = None,
       # ... other parameters
   ) -> list[MessageResponse]:
   

2. GET /api/v1/monitor/transactions (Line 183)

   @router.get("/transactions")  # ❌ Missing authentication
   async def get_transactions(
       flow_id: Annotated[UUID, Query()],
       session: DbSession,
       params: Annotated[Params | None, Depends(custom_params)],
   ) -> Page[TransactionTable]:
   

3. DELETE /api/v1/monitor/messages/session/{session_id} (Line 165)

   @router.delete("/messages/session/{session_id}", status_code=204)  # ❌ Missing authentication
   async def delete_messages_session(
       session_id: str,
       session: DbSession,
   ):
   

Inconsistency Evidence: Other endpoints in the same file properly implement authentication:

@router.get("/messages/sessions", dependencies=[Depends(get_current_active_user)])  # ✅ Properly secured
@router.delete("/messages", status_code=204, dependencies=[Depends(get_current_active_user)])  # ✅ Properly secured

PoC

Complete reproduction steps to demonstrate the vulnerability:...