The WP STAGING WordPress Backup Plugin before 3.1.3 and WP STAGING Pro WordPress Backup Plugin before 5.1.3 do not prevent visitors from leaking key information about ongoing backups processes, allowing unauthenticated attackers to download said backups later.
https://wpscan.com/vulnerability/5a71049a-09a6-40ab-a4e8-44634869d4fb