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CVE-2026-40308— My Calendar: Unauthenticated Information Disclosure (IDOR) via Multisite switch_to_blog

Quick assessment

Affected
joedolson my-calendar
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

WordPress和WordPress plugin都是WordPress基金会的产品。WordPress是一套使用PHP语言开发的博客平台。该平台具有在基于PHP和MySQL的服务器上架设个人博客网站的功能。WordPress plugin是一个应用插件。 WordPress plugin My Calendar 3.7.6及之前版本存在安全漏洞，该漏洞源于mc_ajax_mcjs_action AJAX端点未经身份验证即可访问，且未经验证即传递用户提供的参数，可能导致未经身份验证的攻击者在多站点安装中

AI Predicted 9.8 Difficulty: Trivial EPSS 1.14% · P65

Public Exploits 1

Nuclei · 1 CVE-2026-40308.yaml [template]
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I. Basic Information for CVE-2026-40308

Vulnerability Information
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Vulnerability Title
My Calendar: Unauthenticated Information Disclosure (IDOR) via Multisite switch_to_blog
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
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
Source: CVE Program / CVE List V5
Vulnerability Type
通过用户控制密钥绕过授权机制
Source: CVE Program / CVE List V5
Vulnerability Title
WordPress plugin My Calendar 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
WordPress和WordPress plugin都是WordPress基金会的产品。WordPress是一套使用PHP语言开发的博客平台。该平台具有在基于PHP和MySQL的服务器上架设个人博客网站的功能。WordPress plugin是一个应用插件。 WordPress plugin My Calendar 3.7.6及之前版本存在安全漏洞，该漏洞源于mc_ajax_mcjs_action AJAX端点未经身份验证即可访问，且未经验证即传递用户提供的参数，可能导致未经身份验证的攻击者在多站点安装中
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
joedolson my-calendar < 3.7.7 -

II. Public POCs for CVE-2026-40308

# POC Description Source Link Shenlong Link
1 My Calendar WordPress plugin <= 3.7.6 contains an injection vulnerability caused by unvalidated user input passed to parse_str() in mc_ajax_mcjs_action endpoint, letting unauthenticated attackers access or crash sites via switch_to_blog(), exploit requires WordPress Multisite or Single Site setup. https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2026/CVE-2026-40308.yaml POC Details
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III. Intelligence Information for CVE-2026-40308

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Vendor Advisories for CVE-2026-40308 (1)

IV. Related Vulnerabilities

Same vendor: joedolson
Same weakness: CWE-639

V. Comments for CVE-2026-40308

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