miniOrange JWT Authentication for WP REST APIs plugin for WordPress before 4.8.0 contains an authentication method downgrade vulnerability that allows unauthenticated attackers to bypass administrator-configured authentication by supplying a specific GET parameter without any capability check or nonce verification. Attackers can force the plugin to use Basic HTTP authentication regardless of configured JWT or API token settings, then exploit distinguishable error codes and the absence of rate limiting to perform unthrottled username enumeration and credential guessing attacks.