libxml2 2.6.32 and earlier does not properly detect recursion during entity expansion in an attribute value, which allows context-dependent attackers to cause a denial of service (memory and CPU consumption) via a crafted XML document.
https://www.redhat.com/archives/fedora-package-announce/2008-September/msg00347.html
https://www.redhat.com/archives/fedora-package-announce/2008-September/msg00261.html
https://rhn.redhat.com/errata/RHSA-2008-0836.html
https://bugzilla.redhat.com/show_bug.cgi?id=458086
http://www.vmware.com/security/advisories/VMSA-2008-0017.html
http://www.ubuntu.com/usn/usn-640-1
http://www.debian.org/security/2008/dsa-1631
http://support.apple.com/kb/HT3639
http://support.apple.com/kb/HT3613
http://security.gentoo.org/glsa/glsa-200812-06.xml
http://mail.gnome.org/archives/xml/2008-August/msg00034.html
http://lists.opensuse.org/opensuse-security-announce/2008-09/msg00004.html
http://lists.apple.com/archives/security-announce/2009/Jun/msg00005.html