UnRTF allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code as demonstrated by a file containing the string "{\cb-999999999".
https://security.gentoo.org/glsa/201507-06
https://bugzilla.redhat.com/show_bug.cgi?id=1170233
http://www.securityfocus.com/bid/71430
http://www.openwall.com/lists/oss-security/2014/12/04/15
http://www.mandriva.com/security/advisories?name=MDVSA-2015:007
http://www.debian.org/security/2015/dsa-3158
http://secunia.com/advisories/62811
http://lists.fedoraproject.org/pipermail/package-announce/2015-January/147399.html