Easy Timer < 4.2.2 - Authenticated (Editor+) Remote Code Execution via Shortcode

Description

The Easy Timer plugin for WordPress is vulnerable to Remote Code Execution in all versions up to, and including, 4.2.1 via the plugin's shortcodes. This is due to insufficient restriction of shortcode attributes. This makes it possible for authenticated attackers, with Editor-level access and above, to execute code on the server.