{"id":"CVE-2026-104798","aliases":["EUVD-2026-102653","GHSA-jcj4-jrhq-cjvh"],"status":"published","title":"My Calendar \u003c= 3.8.7 - Unauthenticated Privilege Escalation to 'mcs' Parameter via Reflected Shortcode Injection into 'above' Attribute","description":"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 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.","severity":{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.00471,"percentile":0.41222,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-269"],"published":"2026-10-16T04:27:04Z","modified":"2026-10-16T18:17:20Z","products":[{"vendor":"joedolson","product":"my calendar – accessible event manager"}],"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=\u0026old=3746389%40my-calendar\u0026new=3746389%40my-calendar"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-104798"},{"url":"https://github.com/advisories/GHSA-jcj4-jrhq-cjvh"}],"sources":{"cve":[{"id":"CVE-2026-104798","title":"My Calendar \u003c= 3.8.7 - Unauthenticated Privilege Escalation to 'mcs' Parameter via Reflected Shortcode Injection into 'above' Attribute","description":"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 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.","status":"published","published":"2026-10-16T04:27:04.876Z","modified":"2026-10-16T17:07:17.621Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical","assessor":"cna"}],"cwes":["CWE-269"],"updated_at":"2026-11-02T14:20:09.098623Z"}],"euvd":[{"id":"EUVD-2026-102653","description":"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 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.","status":"published","published":"2026-10-16T04:27:04Z","modified":"2026-10-16T17:07:17Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical"}],"updated_at":"2026-11-02T17:00:04.71095Z"}],"ghsa":[{"id":"GHSA-jcj4-jrhq-cjvh","title":"The My Calendar – Accessible Event Manager plugin for WordPress is vulnerable to Privilege...","description":"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 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.","status":"published","published":"2026-10-16T06:30:26Z","modified":"2026-10-16T06:30:32Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical"}],"cwes":["CWE-269"],"updated_at":"2026-11-02T15:13:50.508143Z"}],"nvd":[{"id":"CVE-2026-104798","description":"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 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.","status":"published","published":"2026-10-16T05:17:28.58Z","modified":"2026-10-16T18:17:20.36Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical","assessor":"secondary"}],"cwes":["CWE-269"],"updated_at":"2026-11-02T14:12:59.751798Z"}]}}