The Breeze - WordPress Cache Plugin plugin for WordPress is vulnerable to unauthorized cache clearing in all versions up to, and including, 2.2.21. This is due to the REST API endpoint `/wp-json/breeze/v1/clear-all-cache` being registered with `permission_callback => '__return_true'` and authentication being disabled by default when the API is enabled. This makes it possible for unauthenticated attackers to clear all site caches (page cache, Varnish, and Cloudflare) via a simple POST request, granted the administrator has enabled the API integration feature.