# CVE-2026-30927: Admidio: Event participation IDOR - non-leaders can register other users for events via user_uuid parameter

> Attackers can register or cancel other users for events by manipulating the user_uuid parameter, bypassing leader-only restrictions.

- **Severity:** Medium 5.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 9 Mar 2026
- **Updated:** 10 Mar 2026
- **Also known as:** GHSA-7pfv-hr63-h7cw

## What is CVE-2026-30927?

CVE-2026-30927 is a medium-severity missing authorization vulnerability in admidio, published on 9 Mar 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Admidio is an open-source user management solution. Prior to 5.0.6, in modules/events/events_function.php, the event participation logic allows any user who can participate in an event to register OTHER users by manipulating the user_uuid GET parameter. The condition uses || (OR), meaning if possibleToParticipate() returns true (event is open for participation), ANY user - not just leaders - can specify a different user_uuid and register/cancel participation for that user. The code then operates on $user->getValue('usr_id') (the target user from user_uuid) rather than the current user. This vulnerability is fixed in 5.0.6.

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

## Which versions are affected by CVE-2026-30927?

2 open source packages ship an affected version, including admidio/admidio. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `admidio/admidio` | Packagist | All versions | 5.0.6 |
| `admidio/admidio` | Packagist | All versions | 5.0.6 |

Products: Admidio Admidio.

## How do I fix CVE-2026-30927?

Upgrade admidio/admidio to 5.0.6 or later.

## Is CVE-2026-30927 being exploited?

There is no known exploitation of CVE-2026-30927 in the wild and no public exploit code.

## Other vulnerabilities in admidio

- [CVE-2024-37906](https://insights.sbomify.com/CVE-2024-37906/): Admidio has Blind SQL Injection in ecard_send.php (critical 10.0)
- [CVE-2021-32630](https://insights.sbomify.com/CVE-2021-32630/): Various (critical 9.6)
- [CVE-2026-32817](https://insights.sbomify.com/CVE-2026-32817/): Admidio is Missing Authorization and CSRF Protection on Document and Folder Deletion (critical 9.1)
- [CVE-2024-38529](https://insights.sbomify.com/CVE-2024-38529/): Admidio Vulnerable to RCE via Arbitrary File Upload in Message Attachment (critical 9.1)
- [CVE-2026-32756](https://insights.sbomify.com/CVE-2026-32756/): Admidio: Unrestricted File Upload via CSRF Token Validation Bypass in Documents & Files Module (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-30927 and fix it if it is affected.

What it is: CVE-2026-30927 is a medium-severity missing authorization vulnerability in admidio, published on 9 Mar 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-30927 in the wild and no public exploit code.

Affected packages and fixed versions:
- admidio/admidio (Packagist): affected all versions; fixed in 5.0.6
- admidio/admidio (Packagist): affected all versions; fixed in 5.0.6

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-2026-30927/ (Markdown: https://insights.sbomify.com/CVE-2026-30927/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-30927
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-30927
- OSV: https://osv.dev/vulnerability/CVE-2026-30927

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-30927/
Summaries are generated and may contain mistakes; the official description above is the record.