MaxSite CMS mail_send Plugin cross site scripting

A security vulnerability has been detected in MaxSite CMS up to 109.3. Affected by this issue is some unknown functionality of the component mail_send Plugin. The manipulation of the argument f_subject/f_files/f_from leads to cross site scripting. The attack can be initiated remotely. The exploit has been disclosed publicly and may be used. Upgrading to version 109.4 can resolve this issue. The identifier of the patch is 8a3946bd0a54bfb72a4d57179fcd253f2c550cd7. It is advisable to upgrade the affected component. The vendor was informed early about this issue. They classify it as a "Self-XSS". They deployed a countermeasure: "Nevertheless, we consider this a violation of secure coding standards. The lack of filtering via `htmlspecialchars()` has already been fixed in the latest patch to prevent incorrect data display."