CVE-2026-40308

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.

The following products are affected by CVE-2026-40308 vulnerability.

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Here, you will find a curated list of external links that provide in-depth information to CVE-2026-40308.

URL	Resource
https://github.com/joedolson/my-calendar/releases/tag/v3.7.7
https://github.com/joedolson/my-calendar/security/advisories/GHSA-2mvx-f5qm-v2ch