Langflow IDOR Authorization Bypass via User-Controlled Flow ID

Technical Analysis

The vulnerability lies in Langflow's flow execution endpoint, which accepts a flow ID from the request but does not enforce that the authenticated caller actually owns or has been granted access to that flow before running it. An attacker with any valid authenticated session can enumerate or guess victim flow IDs and trigger execution of flows belonging to other users, inheriting whatever credentials, API keys, connected tools, or data sources those flows reference. This crosses agent/tenant boundaries because flows in Langflow often embed secrets (LLM API keys, database credentials, third-party tool tokens) and orchestrate agentic tool calls, so unauthorized execution can lead to secret exfiltration, unauthorized tool invocation, or lateral movement across a multi-tenant agent platform. Because this is listed in CISA KEV with active exploitation confirmed, the risk extends beyond theoretical IDOR to real-world abuse against internet-facing Langflow instances.

Affected Systems

Langflow

Detection Signatures

• Anomalous API requests to flow execution endpoints referencing flow IDs not previously associated with the requesting user session
• High-frequency sequential or randomized flow ID probing patterns in access logs
• Execution of flows immediately after authentication with no prior flow creation/listing activity by that user
• Unexpected outbound calls from flows to LLM providers or tools not normally associated with the authenticated user's account
• Logs showing cross-user flow_id parameters in POST/execute requests

Remediation Steps

1. 1

   Apply vendor patch immediately

   Update Langflow to the fixed version that enforces flow ownership/authorization checks before execution, per CISA KEV due date.

2. 2

   Enforce server-side authorization checks

   Ensure all flow execution, read, and modification endpoints validate that the requesting user owns or has explicit sharing permissions for the target flow ID, not just that they are authenticated.

3. 3

   Rotate embedded secrets

   Rotate API keys and credentials stored within Langflow flows, since they may have been exposed to unauthorized execution.

4. 4

   Audit execution logs

   Review historical flow execution logs for cross-user flow ID access indicating prior exploitation.

5. 5

   Restrict network exposure

   Limit Langflow instances to internal networks or VPN access and apply WAF rules to detect IDOR probing until patched.

6. 6

   Implement per-flow access control lists

   Adopt explicit ACL/RBAC model for flow sharing rather than relying on obscurity of flow IDs.