GHSA-586r-mm5q-xhg2: 
Ruby vulnerability analysis and mitigation

Impact

With hybrid cryptography, an attacker who obtains the encryption key can use it to decrypt data (acting as symmetric encryption rather than asymmetric).

Mitigation

All users running an affected version should upgrade and re-encrypt all data that uses hybrid cryptography. Generate a new key pair (keys will be shorter)

Lockbox.generate_key_pair

Update models, files, and lockboxes to use it

class User < ApplicationRecord
  has_encrypted :email,
    algorithm: "hybrid",
    encryption_key: new_encryption_key,
    decryption_key: new_decryption_key,
    previous_versions: [{algorithm: "hybrid", decryption_key: previous_decryption_key}]
end

And re-encrypt the data

Lockbox.rotate(User, attributes: [:email])

Credits

Thanks to Andrew Evans for reporting this.