The http_basic_authenticate_with method in actionpack/lib/action_controller/metal/http_authentication.rb in the Basic Authentication implementation in Action Controller in Ruby on Rails before 3.2.22.1, 4.0.x and 4.1.x before 4.1.14.1, 4.2.x before 4.2.5.1, and 5.x before 5.0.0.beta1.1 does not use a constant-time algorithm for verifying credentials, which makes it easier for remote attackers to bypass authentication by measuring timing differences.
https://groups.google.com/forum/message/raw?msg=ruby-security-ann/ANv0HDHEC3k/T8Hgq-hYEgAJ
http://www.securitytracker.com/id/1034816
http://www.securityfocus.com/bid/81803
http://www.openwall.com/lists/oss-security/2016/01/25/8
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-updates/2016-02/msg00034.html
http://lists.opensuse.org/opensuse-security-announce/2016-04/msg00053.html
http://lists.fedoraproject.org/pipermail/package-announce/2016-February/178068.html
http://lists.fedoraproject.org/pipermail/package-announce/2016-February/178067.html
http://lists.fedoraproject.org/pipermail/package-announce/2016-February/178047.html
http://lists.fedoraproject.org/pipermail/package-announce/2016-February/178043.html