Importance of stacking entities in a XXE?

Hi there!

I've been trying to understand some concepts regarding XXE attacks. I'm using the incredible content of PortSwigger: [https://portswigger.net/web-security/xxe/blind](https://portswigger.net/web-security/xxe/blind)However, there is a thing that I don't understand and I've been unable to find an answer. I will appreciate any kind of help.

When discussing blind XXE, they mention the importance of hosting a malicious DTD file and then reference it within the XML payload. It is important to use an external DTD because when using external DTD you can …

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