CVE-2016-4047
An issue was discovered in Open-Xchange OX App Suite before 7.8.1-rev8. References to external Open XML document type definitions (.dtd resources) can be placed within .docx and .xslx files. Those resources were requested when parsing certain parts of the generated document. As a result an attacker can track access to a manipulated document. Usage of a document may get tracked and information about internal infrastructure may get exposed.
Source: CVE-2016-4047