Apache Airflow SFTP provider: Path traversal in SFTPHook.retrieve_directory

A path traversal in the SFTP provider (SFTPHook.retrieve_directory / SFTPOperator(operation=get)) let a malicious or compromised remote SFTP server write files outside the configured local destination directory via crafted directory-entry names. No Airflow account is required — the attack surface is any deployment downloading directories from an untrusted SFTP server. Upgrade apache-airflow-providers-sftp to 5.8.1 or later.