There is a possible denial of service vulnerability in Action View (Rails) <5.2.2.1, <5.1.6.2, <5.0.7.2, <4.2.11.1 where specially crafted accept headers can cause action view to consume 100% cpu and make the server unresponsive.
https://weblog.rubyonrails.org/2019/3/13/Rails-4-2-5-1-5-1-6-2-have-been-released/
https://lists.debian.org/debian-lts-announce/2019/03/msg00042.html
https://groups.google.com/forum/#%21topic/rubyonrails-security/GN7w9fFAQeI
https://access.redhat.com/errata/RHSA-2019:1289
https://access.redhat.com/errata/RHSA-2019:1149
https://access.redhat.com/errata/RHSA-2019:1147
https://access.redhat.com/errata/RHSA-2019:0796
http://www.openwall.com/lists/oss-security/2019/03/22/1
http://lists.opensuse.org/opensuse-security-announce/2019-08/msg00001.html
http://lists.opensuse.org/opensuse-security-announce/2019-06/msg00025.html
http://lists.opensuse.org/opensuse-security-announce/2019-05/msg00011.html