After the release of Ruby 2.3.7 on March 28, 2018, the support of the Ruby 2.3 series was in the security maintenance phase. Now, after one year has passed, this phase has ended. Therefore, on March 31, 2019, all support of the Ruby 2.3 series ends. Security and bug fixes from more recent Ruby versions will no longer be backported to 2.3. There wont be any patches of 2.3 either. We highly recommend that you upgrade to Ruby 2.6 or 2.5 as soon as possible.