The xmlStringGetNodeList function in tree.c in libxml2 2.9.3 and earlier, when used in recovery mode, allows context-dependent attackers to cause a denial of service (infinite recursion, stack consumption, and application crash) via a crafted XML document.
https://www.tenable.com/security/tns-2016-18
https://www.debian.org/security/2016/dsa-3593
https://security.gentoo.org/glsa/201701-37
https://h20566.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c05157239
https://access.redhat.com/errata/RHSA-2016:1292
http://www.ubuntu.com/usn/USN-2994-1
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://www.openwall.com/lists/oss-security/2016/03/21/3
http://www.openwall.com/lists/oss-security/2016/03/21/2
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