actionpack/lib/action_dispatch/routing/route_set.rb in Action Pack in Ruby on Rails 4.x before 4.2.5.1 and 5.x before 5.0.0.beta1.1 allows remote attackers to cause a denial of service (superfluous caching and memory consumption) by leveraging an application's use of a wildcard controller route.
https://groups.google.com/forum/message/raw?msg=ruby-security-ann/dthJ5wL69JE/IdvCimtZEgAJ
http://www.securitytracker.com/id/1034816
http://www.securityfocus.com/bid/81677
http://www.openwall.com/lists/oss-security/2016/01/25/16
http://www.debian.org/security/2016/dsa-3464
http://rhn.redhat.com/errata/RHSA-2016-0296.html
http://lists.opensuse.org/opensuse-updates/2016-02/msg00043.html
http://lists.opensuse.org/opensuse-security-announce/2016-04/msg00053.html
http://lists.fedoraproject.org/pipermail/package-announce/2016-February/178067.html
http://lists.fedoraproject.org/pipermail/package-announce/2016-February/178043.html