IBM Langflow OSS: insecure direct object reference

IBM Langflow OSS 1.0.0 through 1.10.1 can allow an authenticated attacker to exploit the SaveToFile component to read and modify another user's uploaded files by specifying absolute paths pointing to victim storage locations. In append mode, the attacker's workflow reads victim file contents, appends attacker-controlled data, and uploads a copy containing victim data to the attacker's namespace (confidentiality breach). In overwrite mode, the attacker can replace victim file contents with arbitrary data (integrity breach). This breaks the storage ownership boundary between users.