libxml2 through 2.9.1 does not properly handle external entities expansion unless an application developer uses the xmlSAX2ResolveEntity or xmlSetExternalEntityLoader 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 libxml2 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.