# CVE-2026-30884: mdjnelson/moodle-mod_customcert Vulnerable to Authorization Bypass Through User-Controlled Key

> Teachers can read and modify certificate elements in unauthorized courses due to missing context verification in the Moodle custom certificate plugin.

- **Severity:** Critical 9.6 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 18 Mar 2026
- **Updated:** 18 Mar 2026
- **Also known as:** GHSA-8pjr-j7r4-ccjx

## What is CVE-2026-30884?

CVE-2026-30884 is a critical missing authorization vulnerability in mdjnelson moodle-mod_customcert, published on 18 Mar 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

mdjnelson/moodle-mod_customcert is a Moodle plugin for creating dynamically generated certificates with complete customization via the web browser. Prior to versions 4.4.9 and 5.0.3, a teacher who holds `mod/customcert:manage` in any single course can read and silently overwrite certificate elements belonging to any other course in the Moodle installation. The `core_get_fragment` callback `editelement` and the `mod_customcert_save_element` web service both fail to verify that the supplied `elementid` belongs to the authorized context, enabling cross-course information disclosure and data tampering. Versions 4.4.9 and 5.0.3 fix the issue.

Weakness: CWE-639 (Authorization Bypass Through User-Controlled Key)

## Which versions are affected by CVE-2026-30884?


## How do I fix CVE-2026-30884?

No fix has been published for CVE-2026-30884 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-30884 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-30884 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-30884 and fix it if it is affected.

What it is: CVE-2026-30884 is a critical missing authorization vulnerability in mdjnelson moodle-mod_customcert, published on 18 Mar 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-30884 exists.

Affected product: mdjnelson moodle-mod_customcert. 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-2026-30884/ (Markdown: https://insights.sbomify.com/CVE-2026-30884/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-30884
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-30884
- OSV: https://osv.dev/vulnerability/CVE-2026-30884

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-30884/
Summaries are generated and may contain mistakes; the official description above is the record.