CVE-2026-40308
HighPublic exploitUnauthenticated Information Disclosure (IDOR) via Multisite switch_to_blog in My Calendar
Published Apr 16, 2026 · Updated Aug 12, 2026 · Also known as 9082adc5-508d-47ac-a74a-868e2600e3d6, GHSA-2mvx-f5qm-v2ch
Key Facts
Patch immediately- CVE-2026-40308 is a high-severity vulnerability (CVSS 8.8 v4) affecting joedolson/my-calendar (composer), my-calendar (wordpress-plugin).
- It is not listed in any known-exploited vulnerabilities catalog. Public exploit code is available.
- EPSS estimates a 1.1% probability of exploitation in the next 30 days.
- Fixed versions are available, including joedolson/my-calendar 3.7.7, my-calendar 3.7.7.
- Brandefense priority: patch immediately, because public exploit code exists for a high-severity flaw.
CVSS v4
8.8
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
EPSS (30-day exploit likelihood)
1.1%
Higher than 65.9% of all scored CVEs
Exploited in the wild
No known
Not in a known-exploited catalog
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2026-40308 brief as a PDF
Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.
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 Products
3 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| joedolson/my-calendarcomposer | See advisory | 3.7.7 |
| my-calendarwordpress-plugin | >= < 3.7.7 | 3.7.7 |
Patched Releases
joedolson/my-calendar
3.7.7
my-calendar
3.7.7
Timeline
Publicly disclosed
Apr 16, 2026
Last updated
Aug 12, 2026
Weakness Type
- CWE-639 Authorization Bypass Through User-Controlled Key
References
- advisoryGHSA advisory
- advisoryhttps://github.com/CVEProject/cvelistV5/tree/main/cves/2026/40xxx/CVE-2026-40308.json
- advisoryhttps://nvd.nist.gov/vuln/detail/CVE-2026-40308
- advisoryhttps://www.wordfence.com/threat-intel/vulnerabilities/id/9082adc5-508d-47ac-a74a-868e2600e3d6?source=api-prod
- advisoryhttps://www.wordfence.com/threat-intel/vulnerabilities/id/9082adc5-508d-47ac-a74a-868e2600e3d6?source=api-scan
FAQ
Common Questions.
My Calendar is a WordPress plugin for managing calendar events.
Affected: joedolson/my-calendar (composer); my-calendar (wordpress-plugin) versions >= < 3.7.7. The full list is in the CVE brief.
It is not listed in any known-exploited vulnerabilities catalog.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
Public exploit code is available.
Fixed versions are available, including joedolson/my-calendar 3.7.7, my-calendar 3.7.7.
Brandefense priority: patch immediately, because public exploit code exists for a high-severity flaw.
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