An issue was discovered in RubyGems 2.6 and later through 3.0.2. Since Gem::CommandManager#run calls alert_error without escaping, escape sequence injection is possible. (There are many ways to cause an error.)
https://lists.debian.org/debian-lts-announce/2020/08/msg00027.html
https://hackerone.com/reports/317353
http://lists.opensuse.org/opensuse-security-announce/2019-07/msg00036.html