Welcome Software Publishing <= 0.0.31 - Authenticated (Subscriber+) Arbitrary Options Update to Privilege Escalation via 'nc.setOption' XML-RPC Method

The Welcome Software Publishing plugin for WordPress is vulnerable to Arbitrary Options Update in all versions up to and including 0.0.31. This is due to a missing capability check in the nc_setOption() function, which is exposed via the nc.setOption XML-RPC method. The function authenticates the user via $wp_xmlrpc_server->login() (verifying credentials are valid) but does not perform any authorization check such as current_user_can('manage_options'). This makes it possible for authenticated attackers, with Subscriber-level access and above, to update arbitrary WordPress options via XML-RPC requests. This can be leveraged to change the default_role option to 'administrator' and then register a new administrator account, achieving full privilege escalation and site takeover.