CVE-2026-77186 Details
Description
The My Calendar – Accessible Event Manager plugin for WordPress is vulnerable to Stored Cross-Site Scripting via 'fallback' Shortcode Attribute in all versions up to, and including, 3.8.3 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The bypass relies on hex-encoded shortcode attribute payloads (e.g. \x3cscript\x3e), which wp_kses_post cannot strip on save because they appear as literal backslash sequences rather than real HTML tags; WordPress core's shortcode_parse_atts() then calls stripcslashes() at render time, decoding the escapes into real angle brackets before they reach the unescaped sink.
A stored cross-site scripting vulnerability has been identified in the My Calendar – Accessible Event Manager plugin for WordPress, affecting all versions through 3.8.3. The vulnerability arises from inadequate input sanitization and output escaping, allowing authenticated attackers with contributor-level access or higher to inject arbitrary web scripts via the 'fallback' shortcode attribute. These injected scripts are executed when a user accesses the affected page. The exploitation takes advantage of hex-encoded shortcode attribute payloads, which bypass the WordPress sanitization functions and are decoded at render time, leading to the execution of malicious scripts.
Users are advised to update the My Calendar – Accessible Event Manager plugin to version 3.8.4 or later.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Sep 9, 2026CISA-ADP
Assessed Sep 9, 2026References to Advisories, Solutions, and Tools
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Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-79 | Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| Joe Dolson My Calendar | <= 3.8.3 (semver) |
CPE
Remediation
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Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Sep 9, 2026 | CVE Modified | CISA-ADP |
| Sep 9, 2026 | New CVE Received | [email protected] |