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...

Published: April 16, 2026 | Last Modified: April 16, 2026

Description

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.

Proof-of-Concept Exploits (1)

• joedolson/my-calendar

Security Coverage (1 articles)

References

• github.com/joedolson/my-calendar/releases/tag/v3.7.7
• github.com/joedolson/my-calendar/security/advisories/GHSA-2mvx-f5qm-v2ch