Simple Calendar <= 3.1.42 - Cross-Site Request Forgery to Transient Cache Clearing

The Simple Calendar plugin for WordPress is vulnerable to Cross-Site Request Forgery in versions up to, and including, 3.1.42. This is due to missing nonce validation on the clear_cache() function used to clear the plugin's transients. This makes it possible for unauthenticated attackers to clear the plugin's transients for a given id, via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.