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

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

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 · score source

EPSS

• CVE-2026-30927: 0.27% estimated exploitation activity in the next 30 days; percentile 19.15 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Vulnerability In modules/events/eventsfunction.php, the event participation logic allows any user who can participate in an event to register OTHER users by manipulating the useruuid GET parameter. Line 47: $getUserUuid = admFuncVariableIsValid($GET, 'useruuid', 'uuid', ...) Line 424: if ($event-possibleToParticipate() || $participants-isLeader($gCurrentUserId)) The condition uses || (OR), meaning if possibleToParticipate() returns true (event is open for participation), ANY user - not just leaders - can specify a different useruuid and register/cancel participation for that user. The code then operates on $user-getValue('usrid') (the target user from useruuid) rather than the current user. Impact - Register unwilling users for events (potential harassment/spam) - Cancel other users' event participation - Manipulate event participant counts and comments - If events have participation limits, fill slots with unwanted registrations Fix For non-leader users, force useruuid to the…

Published by the source

9 Mar 2026, 19:45 UTC

Last modified by the source

10 Mar 2026, 18:39 UTC

Source last checked

26 Oct 2026, 14:38 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-7pfv-hr63-h7cw

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# Patch Next advisory brief: CVE-2026-30927

Advisory: Admidio: Event participation IDOR - non-leaders can register other users for events via user_uuid parameter
IDs: CVE-2026-30927, GHSA-7pfv-hr63-h7cw
Record: https://patchnext.com/advisories/cve-2026-30927 (revision 1, source checked 26 Oct 2026, 14:38 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: admidio/admidio 5.0.6. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist admidio/admidio: affected < 5.0.6; fixed in 5.0.6

## Suggested inspection (read-only)
- Packagist admidio/admidio: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on admidio/admidio.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-7pfv-hr63-h7cw (GitHub-reviewed advisory GHSA-7pfv-hr63-h7cw lists affected ranges: Packagist admidio/admidio >=0 <5.0.6)

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