Since no authentication or authorisation checks for direct access to the jqueryFileTree.php are made, the vulnerability allows for browsing the file system on a host out of an unauthenticated context. Even though no file content can be exfiltrated this way, “hidden” files e.g. in the web directories could easily enumerated this way. E.g. this could be abused for a “file path/name leakage” in another exploitation chain.
curl 'https://example.com/wp-content/plugins/wp-lister-amazon/js/jqueryFileTree/connectors/jqueryFileTree.php' -d "dir=../../"