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high·Product Based Web Vulnerabilities·Updated Apr 22, 2026

CVE-2026-40308 Scanner

CVE-2026-40308 Scanner - Information Disclosure vulnerability in My Calendar WordPress Plugin

Est. Time~10 seconds
Scan TypeSingle Scan
Targetsurl
CostFree
3.2k
Times Used
continuous scan runs
5.9k
Continuously Checked
assets under CS
0
Vulnerabilities Found
confirmed findings
References
CVECVE-2026-40308
8.8
CVSShigh
Exploitable remotely over the internet · no authentication required.

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.

Attack Vector
Network
Privileges Req.
None
User Interaction
None
Affected
my-calendarby joedolson
< 3.7.7
Updated Aug 22, 2026View on NVD →
Detail

My Calendar is a versatile WordPress plugin used to manage and display events across a WordPress-powered website. It's primarily used by bloggers, businesses, and organizations for scheduling purposes. The plugin supports event management across single or multisite WordPress installations. It offers features like event sharing, multisite support, and event search for enhanced user interaction. The plugin's popularity stems from its ease of use and compatibility with numerous WordPress themes. Overall, it provides an effective solution for users looking to implement a calendar feature on their WordPress sites.

The vulnerability in question is an Information Disclosure flaw within the My Calendar WordPress Plugin. This vulnerability allows unauthenticated attackers to view private events if exploited on a WordPress multisite configuration. The flaw results from an insufficient validation process on user inputs, leading to data exposure. In single-site configurations, the vulnerability could lead to denial of service. Such vulnerabilities pose significant risks as they can breach data privacy and impact site functionality.

The vulnerability resides in the plugin's mc_ajax_mcjs_action endpoint. An unvalidated user input flaw allows an attacker to manipulate data using the parse_str() function. This exploitation is possible due to a weakness in handling inputs passed through HTTP GET requests. The flaw specifically targets input processing in WordPress Multisite or Single Site configurations. Attackers leverage this flaw to access information or disrupt services by switching to different blog contexts. Proper validation practices were inadequately applied, leading to this oversight.

If a malicious actor exploits this vulnerability, it can lead to unauthorized information disclosure or service disruption. In a WordPress Multisite setup, the attacker might gain access to confidential event details, risking privacy breaches. On a Single Site setup, the vulnerability could allow attacks leading to denial of service, potentially making the site unreachable. This kind of exposure could have reputational damages, as well as legal repercussions for neglecting user data protection. Furthermore, without immediate fixes, continuous exploitation remains a looming threat to site stability and security.

REFERENCES

Solution Advice
  • Update the My Calendar WordPress Plugin to version 3.7.7 or later to eliminate the vulnerability.
  • Ensure inputs are properly validated and sanitized to prevent unauthorized access or manipulation.
  • Implement regular security audits on plugins and themes to detect similar vulnerabilities before exploitation.
  • Developers should utilize secure coding practices when handling user inputs in web applications.
  • Consider limiting public exposure of administrative endpoints to reduce risk surfaces.

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