CVE-2026-77186
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.
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
Affected products
2- Range: <=3.8.3
Patches
Vulnerability mechanics
References
5- github.com/joedolson/my-calendar/commit/89bbf7314fac84cdb89e520e8b7b6d69eee8dd3cnvd
- plugins.trac.wordpress.org/browser/my-calendar/trunk/my-calendar-shortcodes.phpnvd
- plugins.trac.wordpress.org/browser/my-calendar/trunk/my-calendar-widgets.phpnvd
- plugins.trac.wordpress.org/browser/my-calendar/trunk/my-calendar.phpnvd
- www.wordfence.com/threat-intel/vulnerabilities/id/62c8fb1f-6cba-43cc-8aca-70812c29a63dnvd
News mentions
1- Wordfence Intelligence Weekly WordPress Vulnerability Report (September 7, 2026 to September 13, 2026)Wordfence Blog · Sep 17, 2026