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.

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

Q: 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.

Q: How is CVE-2026-40308 attacked?

It is attacked over the network, in a software library.

Q: 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.

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. Vendors: Joe Dolson, 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
```
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

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