HT Event <= 1.4.5 - Cross-Site Request Forgery leading to Arbitrary Plugin Activation

The HT Event plugin for WordPress is vulnerable to Cross-Site Request Forgery in versions up to, and including, 1.4.5. This is due to missing or incorrect nonce validation on the 'plugin_activation' function. This makes it possible for unauthenticated attackers to activate arbitrary plugins already installed (but deactivated) on the site via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.