Langflow: Unauthenticated Flow Execution via Webhook Authentication Bypass

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):

async def get_webhook_user(self, flow_id: str, request: Request) -> UserRead:
    settings_service = self.settings
    ...
    # VULNERABILITY: If this setting is False (default in = 1.7.0,