My Calendar <= 3.2.17 - Subscriber+ Reflected Cross-Site Scripting
Strategic Overview
- Status
- Patched in 3.2.18
- Affected Plugin
- My Calendar – Accessible Event Manager
- Affected Version
<= 3.2.17- CVSS
- 5.4Medium
- Weakness type
- CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
- CVE
CVE-2021-24927
At a glance
CVE-2021-24927 is a medium-severity Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in the My Calendar WordPress plugin, affecting versions <= 3.2.17. It carries a CVSS score of 5.4 (reachable over the network; low attack complexity). The issue is fixed in version 3.2.18; sites on affected versions should update now. Disclosed November 2021, reported by Krzysztof Zając.
Vulnerability Overview
The My Calendar WordPress plugin before 3.2.18 does not sanitise and escape the callback parameter of the mc_post_lookup AJAX action (available to any authenticated user) before outputting it back in the response, leading to a Reflected Cross-Site Scripting issue
Technical Analysis
The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed.
CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Reaching this weakness in My Calendar <= 3.2.17 takes a caller who can reach the endpoint. Cross-site scripting happens when input from a request is written into a page without being escaped for the context it lands in, so the browser parses attacker-supplied text as markup or script.
Injected script runs with the privileges of whoever views the affected page, which is how these flaws turn into administrator session theft, silent account creation or persistent backdoors in page content. For My Calendar the fix is 3.2.18: builds <= 3.2.17 are affected, anything from 3.2.18 onward is not.
Remediation
Update to version 3.2.18, or a newer patched version
How does WordSec protect against this?
The attempt arrives as an ordinary request to My Calendar: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: My Calendar 3.2.18 closes this, and updating the plugin is the step that ends it.
- Firewall
- Alerts
External References
Related records
Same weakness class
- 6.4CVE-2026-77186: My Calendar <= 3.8.3 Stored Cross-Site Scripting
CVE-2026-77186 - 6.4CVE-2026-77187: My Calendar <= 3.8.3 Stored Cross-Site Scripting
CVE-2026-77187 - 6.4CVE-2026-2355: My Calendar – Accessible Event Manager Stored XSS
CVE-2026-2355 - 6.4CVE-2024-25916: My Calendar <= 3.4.23 Stored Cross-Site Scripting
CVE-2024-25916
Other vulnerabilities in My Calendar – Accessible Event Manager
- 9.8CVE-2023-6360: My Calendar <= 3.4.21 SQL Injection
CVE-2023-6360 - 9.8My Calendar <= 2.3.29 Path Traversal to Remote Code Execution
- 8.8CVE-2023-23813: My Calendar <= 3.4.3 Cross-Site Request Forgery
CVE-2023-23813 - 7.5CVE-2026-6854: My Calendar <= 3.7.8 SQL Injection
CVE-2026-6854 - 7.1CVE-2022-47427: My Calendar <= 3.3.24.1 Cross-Site Request Forgery
CVE-2022-47427 - 6.4My Calendar <= 2.5.16 Stored Cross-Site Scripting
- 6.1CVE-2019-15713: My Calendar <= 3.1.9 Cross-Site Scripting
CVE-2019-15713 - 6.1My Calendar < 2.3.30 Reflected Cross-Site Scripting
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