RubyGems version 2.6.12 and earlier is vulnerable to maliciously crafted gem specifications to cause a denial of service attack against RubyGems clients who have issued a `query` command.
https://www.debian.org/security/2017/dsa-3966
https://security.gentoo.org/glsa/201710-01
https://lists.debian.org/debian-lts-announce/2018/07/msg00012.html
https://hackerone.com/reports/243003
https://github.com/rubygems/rubygems/commit/8a38a4fc24c6591e6c8f43d1fadab6efeb4d6251
https://access.redhat.com/errata/RHSA-2018:0585
https://access.redhat.com/errata/RHSA-2018:0583
https://access.redhat.com/errata/RHSA-2018:0378
https://access.redhat.com/errata/RHSA-2017:3485
http://www.securitytracker.com/id/1039249