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CVE-2026-40308

HIGH 8.8 CVSS 4.0
Published
April 16, 2026
Last modified
June 17, 2026
NVD status
Deferred
Reported by
security-advisories@github.com
Weakness
CWE-639
CVSS vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

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.

Affected WordPress components

A confirmed match is backed by the plugin or theme slug. A possible match is based on the product name only and should be verified.

Affected products and versions

  • joedolson my-calendar — Version < 3.7.7

References

  • github.com https://github.com/joedolson/my-calendar/releases/tag/v3.7.7
  • github.com https://github.com/joedolson/my-calendar/security/advisories/GHSA-2mvx-f5qm-v2ch
  • nvd.nist.gov Official NVD record