Adobe Document Service allows an attacker with administrator privileges to send a crafted request from a vulnerable web application. It is usually used to target internal systems behind firewalls that are normally inaccessible to an attacker from the external network, resulting in a Server-Side Request Forgery vulnerability. On successful exploitation, the attacker can read or modify any file and/or make the entire system unavailable.
The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.