neon before 0.28.6, when expat is used, does not properly detect recursion during entity expansion, which allows context-dependent attackers to cause a denial of service (memory and CPU consumption) via a crafted XML document containing a large number of nested entity references, a similar issue to CVE-2003-1564.
https://www.redhat.com/archives/fedora-package-announce/2009-August/msg00945.html
https://www.redhat.com/archives/fedora-package-announce/2009-August/msg00924.html
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A9461
https://exchange.xforce.ibmcloud.com/vulnerabilities/52633
http://www.vupen.com/english/advisories/2009/2341
http://www.mandriva.com/security/advisories?name=MDVSA-2009:221
http://support.apple.com/kb/HT4435
http://secunia.com/advisories/36371
http://rhn.redhat.com/errata/RHSA-2013-0131.html
http://lists.opensuse.org/opensuse-security-announce/2009-11/msg00004.html
http://lists.manyfish.co.uk/pipermail/neon/2009-August/001045.html
http://lists.manyfish.co.uk/pipermail/neon/2009-August/001044.html
http://lists.apple.com/archives/security-announce/2010//Nov/msg00000.html