URL INjection

Google Console is saying I have a URL Injection located at http://etheridgeassociates.com/sitemap-pdfindex6.xml How do I go about curing this problem. I have looked for the file to no avail and have run wordpress and site scanners but have come up with nothing. I have been trying to read up on this but having trouble finding/understanding everything. This is my first time trying to solve and issue like this so any advice is very much appreciated. Thanks