libxml2 2.9.0 and earlier allows context-dependent attackers to cause a denial of service (CPU and memory consumption) via an XML file containing an entity declaration with long replacement text and many references to this entity, aka "internal entity expansion" with linear complexity.
https://git.gnome.org/browse/libxml2/commit/?id=23f05e0c33987d6605387b300c4be5da2120a7ab
https://bugzilla.redhat.com/show_bug.cgi?id=912400
http://www.ubuntu.com/usn/USN-1782-1
http://www.oracle.com/technetwork/topics/security/cpujan2015-1972971.html
http://www.mandriva.com/security/advisories?name=MDVSA-2013:056
http://www.debian.org/security/2013/dsa-2652
http://secunia.com/advisories/55568
http://secunia.com/advisories/52662
http://marc.info/?l=bugtraq&m=142798889927587&w=2
http://lists.opensuse.org/opensuse-updates/2013-03/msg00114.html
http://lists.opensuse.org/opensuse-updates/2013-03/msg00112.html
http://lists.opensuse.org/opensuse-security-announce/2013-11/msg00002.html