n8n - Arbitrary File Read and Execution via ExecuteWorkflow localFile Parameter

n8n before 2.19.3 contains a file path restriction bypass in the legacy ExecuteWorkflow node's localFile source option, which reads workflow files from disk without the file-access checks enforced by other file-reading nodes. Although hidden from the UI since v1.2, it remains reachable via the REST API. An authenticated user with permission to create or modify workflows can supply an arbitrary file path to bypass the N8N_RESTRICT_FILE_ACCESS_TO restriction and determine whether arbitrary files exist on the host; where the targeted path contains a valid workflow JSON file, that file can additionally be loaded and executed.