Affected: IBM Langflow OSS

IBM Langflow OSS 1.0.0 through 1.10.0 has a vulnerability in Langflow's webhook authentication logic allows unauthenticated users to trigger the execution of any flow. The system incorrectly bypasses API key validation when the WEBHOOK_AUTH_ENABLE configuration is set to False (which is the default setting). This allows a remote attacker who knows a flow's UUID to execute it as if they were the owner, potentially leading to Remote Code Execution (RCE).

Affected: PyPI: langflow

### Summary A vulnerability in Langflow's webhook authentication logic allows unauthenticated users to trigger the execution of any flow. The system incorrectly bypasses API key validation when the `WEBHOOK_AUTH_ENABLE` configuration is set to `False`. This allows a remote attacker who knows a flow's UUID to execute it as if they were the owner, potentially leading to Remote Code Execution (RCE) or Denial of Service (DoS).

### Details The `WEBHOOK_AUTH_ENABLE` setting was introduced in v1.7.0 (#9139) with a default of `False`. The root cause is in the webhook authentication path, `AuthService.get_webhook_user` (`src/backend/base/langflow/services/auth/service.py`; the thin wrapper in `src/backend/base/langflow/services/auth/utils.py` just delegates to it):

```python async def get_webhook_user(self, flow_id: str, request: Request) -> UserRead: settings_service = self.settings ... # VULNERABILITY: If this setting is False (default in <= 1.9.0), it returns # the flow owner WITHOUT checking the API Key in the request. if not settings_service.auth_settings.WEBHOOK_AUTH_ENABLE: try: flow_owner = await get_user_by_flow_id_or_endpoint_name(flow_id) return flow_owner ```

By default (v1.7.0 through v1.9.0), Langflow treats `WEBHOOK_AUTH_ENABLE` as `False`, meaning all webhook endpoints are public. This relies exclusively on the secrecy of the `flow_id` (UUID), which is an insecure practice (Security by Obscurity).

A related repor…