parser.c in libxml2 before 2.9.2 does not properly prevent entity expansion even when entity substitution has been disabled, which allows context-dependent attackers to cause a denial of service (CPU consumption) via a crafted XML document containing a large number of nested entity references, a variant of the "billion laughs" attack.
http://kb.juniper.net/InfoCenter/index?page=content&id=JSA10705
http://lists.apple.com/archives/security-announce/2015/Aug/msg00001.html
http://lists.apple.com/archives/security-announce/2015/Aug/msg00002.html
http://lists.opensuse.org/opensuse-updates/2014-10/msg00034.html
http://lists.opensuse.org/opensuse-updates/2015-12/msg00120.html
http://rhn.redhat.com/errata/RHSA-2014-1655.html
http://rhn.redhat.com/errata/RHSA-2014-1885.html
https://bugzilla.redhat.com/attachment.cgi?id=944444&action=diff
https://bugzilla.redhat.com/show_bug.cgi?id=1149084
http://secunia.com/advisories/59903
http://secunia.com/advisories/61965
http://secunia.com/advisories/61966
http://secunia.com/advisories/61991
https://support.apple.com/kb/HT205030
https://support.apple.com/kb/HT205031
http://www.debian.org/security/2014/dsa-3057
http://www.mandriva.com/security/advisories?name=MDVSA-2014:244
http://www.openwall.com/lists/oss-security/2014/10/17/7
http://www.oracle.com/technetwork/topics/security/bulletinjan2015-2370101.html
http://www.oracle.com/technetwork/topics/security/ovmbulletinjul2016-3090546.html