{"id":"CVE-2026-104798","title":"My Calendar <= 3.8.7 - Unauthenticated Privilege Escalation to 'mcs' Parameter via Reflected Shortcode Injection into 'above' Attribute","summary":"The My Calendar – Accessible Event Manager plugin for WordPress is vulnerable to Privilege Escalation in all versions up to, and including, 3.8.7. The public `mcs` GET parameter is reflected into post content unsanitized before WordPress…","severity":"critical","cvss":9.8,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","cwe":["CWE-269"],"vendor":"joedolson","product":"My Calendar – Accessible Event Manager","affected":["my_calendar_accessible_event_manager <= 3.4.24","my_calendar_accessible_event_manager >= 3.5 <= 3.5.21","my_calendar_accessible_event_manager >= 3.6 <= 3.6.17","my_calendar_accessible_event_manager >= 3.7 <= 3.7.17","my_calendar_accessible_event_manager >= 3.8 <= 3.8.7"],"ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"total","timestamp":"2026-10-16T16:48:56.803700Z"},"published":"2026-10-16","updated":"2026-10-16","sourceUpdated":"2026-10-16T17:07:17.621Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-104798","references":[{"url":"https://www.wordfence.com/threat-intel/vulnerabilities/id/e8aa6ee7-525e-4458-9f5b-1e729afe448c?source=cve"},{"url":"https://plugins.trac.wordpress.org/browser/my-calendar/tags/3.8.6/my-calendar-navigation.php#L248"},{"url":"https://plugins.trac.wordpress.org/browser/my-calendar/tags/3.8.6/my-calendar-navigation.php#L260"},{"url":"https://plugins.trac.wordpress.org/browser/my-calendar/tags/3.8.6/my-calendar-search.php#L221"},{"url":"https://plugins.trac.wordpress.org/browser/my-calendar/tags/3.8.6/my-calendar-search.php#L170"},{"url":"https://plugins.trac.wordpress.org/browser/my-calendar/tags/3.8.6/my-calendar-shortcodes.php#L102"},{"url":"https://plugins.trac.wordpress.org/browser/my-calendar/tags/3.8.6/my-calendar-output.php#L1622"},{"url":"https://plugins.trac.wordpress.org/changeset?reponame=&old=3746389%40my-calendar&new=3746389%40my-calendar"}],"tags":["cve.org"],"epss":0.00891,"epssPercentile":0.58638,"ingestedAt":"2026-10-16T04:58:47.490Z","slug":"CVE-2026-104798","body":"## Overview\n\nThe My Calendar – Accessible Event Manager plugin for WordPress is vulnerable to Privilege Escalation in all versions up to, and including, 3.8.7. The public `mcs` GET parameter is reflected into post content unsanitized before WordPress core's `do_shortcode` filter runs, allowing an unauthenticated attacker to inject a nested `[my_calendar above=...]` shortcode; `mc_generate_calendar_nav()` then splits the `above` attribute on commas and dispatches each element via `call_user_func()` with no authentication, authorization, or callable allowlist check. This makes it possible for unauthenticated attackers to invoke arbitrary loaded PHP functions, enabling a call chain in which the shortcode `$params` array is passed to `edit_user()` — which PHP coerces to integer `1` as the `$user_id` argument — overwriting the credentials of the initial Administrator account (user ID 1) and granting the attacker full wp-admin access. Exploitation is trivially reachable via the plugin's auto-generated `/my-calendar/` page, which is publicly accessible by default upon plugin activation.\n\n## Affected\n\n- `my_calendar_accessible_event_manager <= 3.4.24`\n- `my_calendar_accessible_event_manager >= 3.5 <= 3.5.21`\n- `my_calendar_accessible_event_manager >= 3.6 <= 3.6.17`\n- `my_calendar_accessible_event_manager >= 3.7 <= 3.7.17`\n- `my_calendar_accessible_event_manager >= 3.8 <= 3.8.7`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"midnight","depthScore":54,"depthScoreParts":{"impact":53.9,"likelihood":0.2,"exploitation":0,"ransomware":0},"changes":[]}