However, their last report states many instances of the following issue, with various files:
... Sicherheitslücke vom Typ "XSS" in WordPress /home/..../website/mediaelement-4.2.9/lang/uk.js ...
With the following explanation:
XSS vulnerability in the Flash fallback files in MediaElement
An XSS vulnerability was discovered in the Flash fallback files in MediaElement, a library that was included with WordPress. Because the Flash files are no longer needed for most use cases, they have been removed from WordPress.
Note: This is a media player, not a form processor.
Note 2: The mention of WordPress is another issue, since this is not a WordPress installation, but this is not part of the question here.