The WPvivid — Backup, Migration & Staging WordPress plugin before 0.9.137 does not sanitize the staging destination folder supplied to its staging-start handler, applying only a generic text filter while the sibling writability-check handler applies the correct filename sanitizer, so an authenticated administrator can supply a path containing traversal sequences and make the WPvivid — Backup, Migration & Staging WordPress plugin before 0.9.137 write the copied site files outside the WordPress installation directory.