XML external entity injection, or XXE for short, is a flaw in online security that allows an attacker to interfere with an application's processing of XML data. This flaw is also known as the XML external entity injection vulnerability. An attacker is frequently granted the ability to examine files located on the disc of the application server and to communicate with any back-end or external systems that the programme itself may access. An attacker can escalate a XXE attack to compromise the underlying server or other back-end infrastructure in certain circumstances by leveraging the XXE vulnerability to perform server-side request forgery (SSRF) attacks. This can be done by exploiting the XXE vulnerability to perform server-side request forgery attacks.