CVE Catalog

CVE-2026-40308

High
Published: Translated: NVD NIST

Summary

My Calendar (WordPress plugin) versions 3.7.6 and below have a vulnerability in the mc_ajax_mcjs_action AJAX endpoint, registered for unauthenticated users. User-supplied arguments are passed through parse_str() without validation, allowing injection of arbitrary parameters including a site value. On WordPress Multisite, this enables an unauthenticated attacker to call switch_to_blog() and extract calendar events from any sub-site, including private ones. On Single Site, it causes an uncaught PHP fatal error and crashes the worker thread (DoS).

Risk Assessment

The risk includes unauthorized access to calendar events (including private) in Multisite and a DoS attack in Single Site.

Recommendation

Upgrade to version 3.7.7 which contains the fix.

Related vulnerabilities

Original NVD description (English source)

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.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS