A possible escalation to RCE vulnerability exists when using YAML serialized columns in Active Record < 7.0.3.1, <6.1.6.1, <6.0.5.1 and <5.2.8.1 which could allow an attacker, that can manipulate data in the database (via means like SQL injection), the ability to escalate to an RCE.
https://groups.google.com/g/rubyonrails-security/c/MmFO3LYQE8U