CVE-2026-77186— My Calendar <= 3.8.3 - Authenticated (Contributor+) Stored Cross-Site Scripting via 'fallback' Shortcode Attribute
Quick assessment
Affected
joedolson My Calendar – Accessible Event Manager
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.
WordPress 的“My Calendar – Accessible Event Manager”插件在所有版本（包括 3.8.3 及之前版本）中，由于输入数据未充分净化且输出未转义，存在通过“fallback”短代码属性引发的存储型跨站脚本（Stored XSS）漏洞。这使得拥有“贡献者（Contributor）”权限或更高权限的认证攻击者，能够将任意 Web 脚本注入到页面中，当用户访问被注入的页面时，这些脚本将会被执行。该漏洞的绕过机制依赖于使用十六进制编码的短代码属性负载（例如 ）。由于这些负载在保存时
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I. Basic Information for CVE-2026-77186
Vulnerability Information
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Vulnerability Title
My Calendar <= 3.8.3 - Authenticated (Contributor+) Stored Cross-Site Scripting via 'fallback' Shortcode Attribute
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
在Web页面生成时对输入的转义处理不恰当(跨站脚本)
Source: CVE Program / CVE List V5
Affected Products
| Vendor | Product | Affected Versions | CPE | Subscribe |
|---|---|---|---|---|
| joedolson | My Calendar – Accessible Event Manager | 0 ~ 3.8.3 | - |
|
II. Public POCs for CVE-2026-77186
| # | POC Description | Source Link | Shenlong Link |
|---|
AI-Generated POC
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Other References for CVE-2026-77186 (5)
IV. Related Vulnerabilities
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V. Comments for CVE-2026-77186
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