The (1) xmlParserEntityCheck and (2) xmlParseAttValueComplex functions in parser.c in libxml2 2.9.3 do not properly keep track of the recursion depth, which allows context-dependent attackers to cause a denial of service (stack consumption and application crash) via a crafted XML document containing a large number of nested entity references.
https://www.tenable.com/security/tns-2016-18
https://www.debian.org/security/2016/dsa-3593
https://security.gentoo.org/glsa/201701-37
https://kc.mcafee.com/corporate/index?page=content&id=SB10170
https://h20566.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c05157239
https://bugzilla.gnome.org/show_bug.cgi?id=765207
https://access.redhat.com/errata/RHSA-2016:1292
http://www.ubuntu.com/usn/USN-2994-1
http://www.securityfocus.com/bid/89854
http://www.oracle.com/technetwork/topics/security/ovmbulletinjul2016-3090546.html
http://www.oracle.com/technetwork/topics/security/linuxbulletinjul2016-3090544.html
http://www.oracle.com/technetwork/topics/security/bulletinjul2016-3090568.html
http://seclists.org/fulldisclosure/2016/May/10
http://rhn.redhat.com/errata/RHSA-2016-2957.html
http://lists.opensuse.org/opensuse-updates/2016-05/msg00127.html
http://lists.opensuse.org/opensuse-updates/2016-05/msg00055.html