New User Approve <= 3.0.9 - Unauthenticated Sensitive Information Disclosure via Type Juggling

The New User Approve plugin for WordPress is vulnerable to unauthorized data disclosure in all versions up to, and including, 3.0.9 due to insufficient API key validation using loose equality comparison. This makes it possible for unauthenticated attackers to retrieve personally identifiable information (PII), including usernames and email addresses of users with various approval statuses via the Zapier REST API endpoints, by exploiting PHP type juggling with the api_key parameter set to "0" on sites where the Zapier API key has not been configured.