The ACF Photo Gallery Field WordPress plugin before 1.7.5 does not sanitise and escape the post parameter in the includes/acf_photo_gallery_metabox_edit.php file before outputing back in an attribute, leading to a Reflected Cross-Site Scripting issue
https://wpscan.com/vulnerability/5855f1fe-28f6-4cd6-a83c-95c23d809b79