The DocumentAnalysisRequestHandler in Apache Solr before 4.3.1 does not properly use the EmptyEntityResolver, which allows remote attackers to have an unspecified impact via XML data containing an external entity declaration in conjunction with an entity reference, related to an XML External Entity (XXE) issue. NOTE: this vulnerability exists because of an incomplete fix for CVE-2013-6407.
https://issues.apache.org/jira/browse/SOLR-4881
http://www.openwall.com/lists/oss-security/2013/11/29/2
http://svn.apache.org/viewvc/lucene/dev/branches/branch_4x/solr/CHANGES.txt?view=markup
http://secunia.com/advisories/59372
http://secunia.com/advisories/55542