Offsprout Page Builder 2.2.1-2.15.2 is vulnerable to Authenticated (Contributor+) Privilege Escalation via permission_callback Function

The Offsprout Page Builder plugin for WordPress is vulnerable to Privilege Escalation due to improper authorization placed on the permission_callback() function in versions 2.2.1 to 2.15.2. This makes it possible for authenticated attackers, with Contributor-level access and above, to read, create, update or delete any user meta, including flipping their own wp_capabilities to administrator and fully escalate their privileges.