The SP Rental Manager WordPress plugin is vulnerable to SQL Injection via the orderby parameter found in the ~/user/shortcodes.php file which allows attackers to retrieve information contained in a site's database, in versions up to and including 1.5.3.
https://www.wordfence.com/vulnerability-advisories/#CVE-2021-38324
https://plugins.trac.wordpress.org/browser/sp-rental-manager/tags/1.5.3/user/shortcodes.php#L389