A CSRF forgery vulnerability exists in rails < 5.2.5, rails < 6.0.4 that makes it possible for an attacker to, given a global CSRF token such as the one present in the authenticity_token meta tag, forge a per-form CSRF token.
https://www.debian.org/security/2020/dsa-4766
https://hackerone.com/reports/732415
https://groups.google.com/g/rubyonrails-security/c/NOjKiGeXUgw