---
cve: "CVE-2026-104798"
severity: "CRITICAL"
cvss: 9.8
epss: ""
vendor: "joedolson"
kev: false
exploited: false
published: "2026-10-16 04:27:04"
tags: [cve, security, critical]
source: tsecurity.de CVE-Dossier
exported: "2026-10-23T10:23:29+02:00"
---

# CVE-2026-104798

> 9.8 CRITICAL

## Beschreibung

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.

## CNA-Record (Kanon, cvelistV5)

- CNA: **Wordfence**
- State: PUBLISHED
- Stand: 2026-10-16 17:07:17
- CNA-CVSS: **9.8** (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)

## CISA-Anreicherung (vulnrichment/ADP)

- CISA-SSVC (Coordinator, v2.0.3):
  - Exploitation: **none**
  - Automatable: **yes**
  - Technical Impact: **total**

## CVSS-Vektor

```
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |
| S Scope | Unverändert | good |
| C Vertraulichkeit | Hoch | bad |
| I Integrität | Hoch | bad |
| A Verfügbarkeit | Hoch | bad |

## Schwachstellen-Klasse

- **CWE-269** — Improper Privilege Management
  The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor.

## Angriffsmuster (CAPEC)

- [CAPEC-58 — Restful Privilege Elevation](https://capec.mitre.org/data/definitions/58.html) _(Severity: High)_
- [CAPEC-122 — Privilege Abuse](https://capec.mitre.org/data/definitions/122.html) _(Severity: Medium)_
- [CAPEC-233 — Privilege Escalation](https://capec.mitre.org/data/definitions/233.html)

## ATT&CK-Techniken

- [T1548 — Abuse Elevation Control Mechanism](https://attack.mitre.org/techniques/T1548/)

## Referenzen

- <https://www.wordfence.com/threat-intel/vulnerabilities/id/e8aa6ee7-525e-4458-9f5b-1e729afe448c?source=cve>
- <https://plugins.trac.wordpress.org/browser/my-calendar/tags/3.8.6/my-calendar-navigation.php#L248>
- <https://plugins.trac.wordpress.org/browser/my-calendar/tags/3.8.6/my-calendar-navigation.php#L260>
- <https://plugins.trac.wordpress.org/browser/my-calendar/tags/3.8.6/my-calendar-search.php#L221>
- <https://plugins.trac.wordpress.org/browser/my-calendar/tags/3.8.6/my-calendar-search.php#L170>
- <https://plugins.trac.wordpress.org/browser/my-calendar/tags/3.8.6/my-calendar-shortcodes.php#L102>
- <https://plugins.trac.wordpress.org/browser/my-calendar/tags/3.8.6/my-calendar-output.php#L1622>
- <https://plugins.trac.wordpress.org/changeset?reponame=&old=3746389%40my-calendar&new=3746389%40my-calendar>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/sicherheitsluecken/cve-2026-104798/) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI WID (CSAF)_