Executive brief
IBM Langflow OSS is an open-source workflow automation platform that manages files uploaded by users through local and cloud storage. A flaw in access control allows authenticated users to read arbitrary files on the system and access files belonging to other users, potentially exposing sensitive data including application secrets used to encrypt stored credentials.
Technical details
The vulnerability is a path traversal and improper access control flaw (CWE-22, CWE-284, CWE-639) affecting Langflow's file handling in flow execution. The tweaks API accepts attacker-controlled file paths without invoking containment guards, allowing traversal sequences to escape the configured data directory. Additionally, when S3 storage is configured with the LANGFLOW_RESTRICT_LOCAL_FILE_ACCESS flag, a code path detecting pre-existing local files bypasses the confinement check entirely. An authenticated attacker can supply another user's storage namespace through the /api/v1/run/advanced/{flow_id} endpoint to read files belonging to other users in multi-user deployments. The attack requires authentication but no user interaction; it affects confidentiality with potential exposure of application secrets. IBM recommends upgrading to version 1.11.6 or later.
Affected products
- IBM Langflow OSS 1.0.0 through 1.11.5
Timeline
- 2026-09-10: disclosed
- 2026-09-08: patched: Version 1.11.6 available