Langflow Authorization Bypass Through User-Controlled Key Vulnerability. Actively exploited: CISA added this vulnerability to its Known Exploited Vulnerabilities catalog on 07/07/2026. Patch affected systems as an emergency.
| Package | Affected versions | Patched versions |
|---|---|---|
| langflow | < 1.9.1< 1.9.2 | 1.9.11.9.2 |
| langflow | < 1.9.1 | 1.9.1 |
Insecure Direct Object Reference (IDOR) vulnerability in /api/v1/responses endpoint allows an authenticated attacker to execute any flow belonging to another user by specifying the victim's flow ID in the request.
The vulnerability exists in the get_flow_by_id_or_endpoint_name helper function in src/backend/base/langflow/helpers/flow.py (lines 399-414).
When a flow is accessed via UUID (flow_id), the function queries the database directly without verifying if the authenticated user owns that flow:
# src/backend/base/langflow/helpers/flow.py:399-414
async def get_flow_by_id_or_endpoint_name(flow_id_or_name: str, user_id: str | UUID | None = None) -> FlowRead:
async with session_scope() as session:
try:
flow_id = UUID(flow_id_or_name)
# When using UUID, query directly WITHOUT checking user_id
flow = await session.get(Flow, flow_id) # ❌ No user_id check!
except ValueError:
endpoint_name = flow_id_or_name
stmt = select(Flow).where(Flow.endpoint_name == endpoint_name)
# Only when using endpoint_name is user_id checked
if user_id:
stmt = stmt.where(Flow.user_id == uuid_user_id)
This function is used by the /api/v1/responses endpoint (defined in src/backend/base/langflow/api/v1/openai_responses.py:589).
# Attacker (user A) with API_KEY_A tries to execute victim (user B)'s flow
curl -X POST "http://localhost:7860/api/v1/responses" \
-H "x-api-key: sk-ATTACKER_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"model": "VICTIM_FLOW_ID",
"input_value": "test",
"stream": false
}'
# Returns 200 and executes the victim's flow
Any authenticated user can:
Fixed in PR #12832 (fix(security): close IDOR in get_flow_by_id_or_endpoint_name), merged 2026-04-22, released in Langflow 1.9.1.
The helper normalizes user_id once and enforces ownership on both lookup branches (UUID and endpoint_name):
flow_id = UUID(flow_id_or_name)
flow = await session.get(Flow, flow_id)
if flow is not None and uuid_user_id is not None and flow.user_id != uuid_user_id:
flow = None # cross-user lookup falls through to the shared 404
Key points:
/api/v1/responses and /api/v2/workflow pass user_id explicitly, so fixing the helper closes them directly; the /api/v1/run* routes were additionally moved from a bare Depends(get_flow_by_id_or_endpoint_name) to auth-aware wrapper dependencies (defense in depth).user_id now fails closed (404 instead of a raw 500)./api/v1/responses.Thanks to the security researchers who responsibly disclosed this vulnerability:
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