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.

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Fixes

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History

Wed, 09 Sep 2026 14:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Wed, 09 Sep 2026 03:45:00 +0000

Type Values Removed Values Added
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.
Title My Calendar <= 3.8.3 - Authenticated (Contributor+) Stored Cross-Site Scripting via 'fallback' Shortcode Attribute
Weaknesses CWE-79
References
Metrics cvssV3_1

{'score': 6.4, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N'}


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cve-icon MITRE

Status: PUBLISHED

Assigner: Wordfence

Published:

Updated: 2026-09-09T13:12:36.335Z

Reserved: 2026-08-20T16:36:39.274Z

Link: CVE-2026-77186

cve-icon Vulnrichment

Updated: 2026-09-09T13:12:26.182Z

cve-icon NVD

Status : Received

Published: 2026-09-09T04:19:55.880

Modified: 2026-09-09T14:17:16.923

Link: CVE-2026-77186

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-09-09T12:00:08Z

Weaknesses