ruby is vulnerable to XML entity expansion (XEE). A remote attacker is able to crash the process using a malicious XML document that would could cause REXML to use an excessive amount of CPU and memory.
advisories.mageia.org/MGASA-2014-0472.html
lists.apple.com/archives/security-announce/2015/Sep/msg00008.html
lists.opensuse.org/opensuse-updates/2014-12/msg00035.html
lists.opensuse.org/opensuse-updates/2015-01/msg00000.html
lists.opensuse.org/opensuse-updates/2015-01/msg00004.html
rhn.redhat.com/errata/RHSA-2014-1911.html
rhn.redhat.com/errata/RHSA-2014-1912.html
rhn.redhat.com/errata/RHSA-2014-1913.html
rhn.redhat.com/errata/RHSA-2014-1914.html
secunia.com/advisories/59948
secunia.com/advisories/62050
secunia.com/advisories/62748
www.debian.org/security/2015/dsa-3157
www.debian.org/security/2015/dsa-3159
www.mandriva.com/security/advisories?name=MDVSA-2015:129
www.oracle.com/technetwork/topics/security/linuxbulletinjan2016-2867209.html
www.securityfocus.com/bid/71230
www.ubuntu.com/usn/USN-2412-1
access.redhat.com/security/updates/classification/#moderate
rhn.redhat.com/errata/RHSA-2014-1911.html
support.apple.com/HT205267
www.ruby-lang.org/en/news/2014/11/13/rexml-dos-cve-2014-8090/