# 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.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 16 Oct 2026
- **Updated:** 16 Oct 2026
- **Also known as:** GHSA-jcj4-jrhq-cjvh

## 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 (Improper Privilege Management)

## 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.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-104798 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-104798 in the wild and no public exploit code.

Affected product: joedolson My Calendar – Accessible Event Manager. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-104798/ (Markdown: https://insights.sbomify.com/CVE-2026-104798/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-104798
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-104798
- OSV: https://osv.dev/vulnerability/CVE-2026-104798

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-104798/
Summaries are generated and may contain mistakes; the official description above is the record.