CVE-2026-104798 Privilege escalation in My Calendar – Accessible Event Manager
Unauthenticated attackers can escalate privileges to Administrator by injecting shortcodes that trigger arbitrary function calls, overwriting admin credentials.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-104798?
CVE-2026-104798 is a critical vulnerability in joedolson My Calendar – Accessible Event Manager, published on 16 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-269
Which versions are affected by CVE-2026-104798?
How do I fix CVE-2026-104798?
No fix has been published for CVE-2026-104798 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-104798 being exploited?
There is no known exploitation of CVE-2026-104798 in the wild and no public exploit code.
Sources
Also known as GHSA-jcj4-jrhq-cjvh.