joedolson/my-calendar

The My Calendar – Accessible Event Manager plugin for WordPress is vulnerable to authorization bypass in all versions up to, and including, 3.7.9. This is due to the plugin not properly verifying that a user is authorized to perform an action. This makes it possible for authenticated attackers, with custom-level access and above, to bypass the moderation and approval workflow by tampering with the POST body to publish events or set other unauthorized statuses such as cancelled or private, in ways their role does not permit. While the UI correctly restricts low-privilege users to a draft-only submit button, this restriction is enforced only client-side, making it trivially bypassable by directly manipulating the POST request.

My Calendar is a WordPress plugin for managing calendar events. In versions 3.7.6 and below, the mc_ajax_mcjs_action AJAX endpoint, registered for unauthenticated users, passes user-supplied arguments through parse_str() without validation, allowing injection of arbitrary parameters including a site value. On WordPress Multisite installations, this enables an unauthenticated attacker to call switch_to_blog() with an arbitrary site ID and extract calendar events from any sub-site on the network, including private or hidden events. On standard Single Site installations, switch_to_blog() does not exist, causing an uncaught PHP fatal error and crashing the worker thread, creating an unauthenticated denial of service vector. This issue has been fixed in version 3.7.7.