On its own this seems a fairly low-impact problem: only DSpace Administrators can set LDN template names in services, and you typically need more access to manipulate files on the server. However, this vulnerability was included as part of an attack chain that demonstrated the ability of a DSpace Administrator to put the malicious Velocity payload in a predictable place (e.g. temporary log file from a running process) and then have that file referenced as the template name in a new service. This means it is possible (non-trivial, but proven) for an attacker with DSpace administrator credentials to either disclose information via a specially crafted Velocity template, or exploit another weakness in the DSpace Velocity implementation by executing arbitrary java code.