expat 2.1.0 and earlier does not properly handle entities expansion unless an application developer uses the XML_SetEntityDeclHandler function which allows remote attackers to cause a denial of service (resource consumption) send HTTP requests to intranet servers or read arbitrary files via a crafted XML document aka an XML External Entity (XXE) issue. NOTE: it could be argued that because expat already provides the ability to disable external entity expansion the responsibility for resolving this issue lies with application developers; according to this argument this entry should be REJECTed and each affected application would need its own CVE.