# CVE-2026-40308: joedolson My Calendar IDOR and DoS in mcjs_action AJAX endpoint

Source: https://junglewise.ai/threats/cve-2026-40308-joedolson-my-calendar-idor-and-dos-in-mcjs-action-ajax-endpoint  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-04-16. Updated: 2026-05-11  
License: CC BY 4.0 with a link back

CVE-2026-40308 · Severity: high · CVSS 4 · Published 2026-04-16

A vulnerability in the My Calendar plugin for WordPress allows unauthorized users to access private calendar events or crash the website. On multi-site networks, an attacker can view private event data from any sub-site. On single-site installations, the same flaw can be used to repeatedly crash the server, leading to a total service outage.

Technologies: [Joe Dolson My Calendar](https://junglewise.ai/threats/technologies/my-calendar). Vendors: [Joe Dolson](https://junglewise.ai/threats/vendors/joe-dolson), [Packagist](https://junglewise.ai/threats/vendors/packagist).

## Quick answers

**Is CVE-2026-40308 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-40308 being exploited in the wild.

**How severe is CVE-2026-40308?** High severity, with a CVSS score of 4, published 16 April 2026.

**Which products and versions are affected?** Joe Dolson My Calendar < 3.7.7; joedolson/my-calendar (Packagist) < 3.7.7, ECOSYSTEM:introduced=0,fixed=3.7.7.

**Is there a fix for CVE-2026-40308?** Yes. joedolson/my-calendar (Packagist): upgrade to 3.7.7 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-40308 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-40308?** Check whether you run Joe Dolson My Calendar or joedolson/my-calendar (Packagist) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- joedolson/my-calendar (Packagist): upgrade to 3.7.7 or later

  ```sh
  composer require joedolson/my-calendar:^3.7.7
  ```


## Technical details

The vulnerability exists in the `mc_ajax_mcjs_action` function, which handles the `mcjs_action` AJAX endpoint. The plugin unsafely uses PHP's `parse_str()` on the unvalidated `args` request parameter, allowing attackers to inject arbitrary key-value pairs. When the `site` argument is provided, the plugin calls `switch_to_blog()` without privilege checks. In WordPress Multisite environments, this allows an unauthenticated attacker to switch database contexts and extract private events from any sub-site. In Single Site environments, calling the non-existent `switch_to_blog()` function triggers an uncaught PHP error, allowing for an unauthenticated application-layer Denial of Service (DoS). This is patched in version 3.7.7.

## Affected products

- joedolson My Calendar < 3.7.7

## Identifiers

- CVE-2026-40308
- GHSA-2mvx-f5qm-v2ch

## Timeline

- 2026-04-16: disclosed
- 2026-04-16: advisory
- 2026-04-16: patched: Fixed in version 3.7.7

## References

- [https://api.github.com/users/minhi1](https://api.github.com/users/minhi1)
- [https://github.com/minhi1](https://github.com/minhi1)
- [https://api.github.com/users/minhi1/gists%7B/gist_id%7D](https://api.github.com/users/minhi1/gists%7B/gist_id%7D)
- [https://api.github.com/users/minhi1/repos](https://api.github.com/users/minhi1/repos)
- [https://avatars.githubusercontent.com/u/147674017?v=4](https://avatars.githubusercontent.com/u/147674017?v=4)
- [https://api.github.com/users/minhi1/events%7B/privacy%7D](https://api.github.com/users/minhi1/events%7B/privacy%7D)

## Related threats

- [My Calendar WordPress plugin shortcode injection](https://junglewise.ai/threats/cve-2026-119714-my-calendar-wordpress-plugin-3-8-8-before-3-8-11-contains-a)
- [Joe Dolson My Calendar SQL injection in mc_auth parameter](https://junglewise.ai/threats/cve-2026-6854-joe-dolson-my-calendar-sql-injection-in-mc-auth-parameter)
- [Joe Dolson My Calendar IDOR in vcal parameter](https://junglewise.ai/threats/cve-2026-11896-joe-dolson-my-calendar-idor-in-vcal-parameter)
- [Joe Dolson My Calendar authorization bypass in event editor](https://junglewise.ai/threats/cve-2026-7525-joe-dolson-my-calendar-authorization-bypass-in-event-editor)