IBM Langflow User Identifier Namespace Collision

Technical Analysis

The vulnerability stems from insufficient uniqueness enforcement or scoping of user identifiers within Langflow's namespace handling, likely in how flows, chat sessions, or stored credentials are keyed and retrieved. An attacker who can trigger or predict a colliding identifier may read another user's conversation history, flow configuration, or secrets, and/or inject unauthorized messages into that user's active session or agent memory. Because Langflow is used to orchestrate LLM agent pipelines, this crosses a tenant/session boundary that agent memory and conversational state are expected to enforce, effectively enabling a form of cross-user memory poisoning and data exfiltration. Exploitation requires only remote access to the affected Langflow instance rather than any special privilege, increasing the attack surface for multi-tenant deployments.

Affected Systems

IBM Langflow OSS

Detection Signatures

• Unexpected cross-user data appearing in chat/flow logs
• Duplicate or reused user identifier values in Langflow database/session tables
• Unexplained messages appearing in a session not initiated by the owning user
• Anomalous access patterns to flow/session endpoints using guessed or sequential user IDs

Remediation Steps

1. 1

   Upgrade Langflow

   Update to the patched Langflow release beyond 1.11.1 as soon as it is available from IBM/Langflow maintainers.

2. 2

   Audit user/session identifier generation

   Review identifier assignment logic to ensure global uniqueness and proper namespace scoping, avoiding collisions across tenants or users.

3. 3

   Restrict remote access

   Limit exposure of Langflow instances to trusted networks or VPNs until patched, especially in multi-tenant or shared deployments.

4. 4

   Review logs for exploitation

   Inspect historical session and message logs for signs of cross-user data leakage or unauthorized message injection.

5. 5

   Enforce strict session isolation

   Add application-layer checks that validate ownership of session/user IDs on every read/write operation, not solely relying on the identifier value.