CVE-2026-30927: Admidio Event Participation IDOR - Non-leaders Vulnerability

MODERATE
Advisory Identifier: GHSA-7pfv-hr63-h7cw
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CVSS 0.0
CWE-639
Published
Advisory Summary

CVE-2026-30927 is a MODERATE (CVSS 0.0) event participation idor - non-leaders vulnerability (CWE-639: Authorization Bypass Through User-Controlled Key) affecting Admidio libraries in the Packagist ecosystem. The issue involves event participation idor - non-leaders can register other users for events via user_uuid parameter. Remediation is available by upgrading affected packages to version 5.0.6.

CVE-2026-30927 at a Glance

CVE Identifier CVE-2026-30927
GHSA Identifier GHSA-7pfv-hr63-h7cw
Severity MODERATE
CVSS v3.1 Base Score 0.0
CWE Classification CWE-639: Authorization Bypass Through User-Controlled Key
Affected Product Admidio
Package Ecosystem Packagist
Published Date
Last Updated

Security Impact

CVSS: 0.0

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity None (I:N)
Availability None (A:N)

How to Fix CVE-2026-30927

To remediate this vulnerability, upgrade all affected Admidio dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

admidio/admidio fixed: 5.0.6 
Upgrade admidio/admidio to 5.0.6
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for admidio/admidio

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-30927, inspect your project dependencies for Admidio:

inspect dependencies for admidio/admidio

Analyze the terminal output to locate any version of Admidio in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 5.0.6), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-639: Authorization Bypass Through User-Controlled Key, where the system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data. In Admidio, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

## Vulnerability 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. Line 47: `$getUserUuid = admFuncVariableIsValid($_GET, 'user_uuid', '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 `user_uuid` and register/cancel participation for that user. The code then operates on `$user->getValue('usr_id')` (the target user from user_uuid) rather than the current user. ## Impact - Register unwilling users for events (potential harassment/spam) - Cancel other users' event participation - Manipulate event participant counts and comments - If events have participation limits, fill slots with unwanted registrations ## Fix For non-leader users, force `user_uuid` to the current user: ```php if (!$participants->isLeader($gCurrentUserId)) { $getUserUuid = $gCurrentUser->getValue('usr_uuid'); } ```

CVE-2026-30927 Affected Admidio Versions

1 component(s)
Fixed Versions:
5.0.6
Product / Package Ecosystem Affected Versions Fixed Version
admidio/admidio
 Packagist
< 5.0.6
5.0.6

References

GitHub Advisory / Wiki ADVISORY
https://github.com/Admidio/admidio/security/advisories/GHSA-7pfv-hr63-h7cw
NVD — CVE-2026-30927 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-30927
Admidio Source Repository REPOSITORY
https://github.com/Admidio/admidio/issues/1985
Security Fix Commit FIX COMMIT
https://github.com/Admidio/admidio/commit/e47f70cc3cbcdb39635fdbaaef02d19f604b8c3e
Admidio Source Repository REPOSITORY
https://github.com/Admidio/admidio

Frequently Asked Questions

What is CVE-2026-30927?
CVE-2026-30927 is a security vulnerability in Admidio involving Event participation IDOR - non-leaders can register other users for events via user_uuid parameter under CWE-639: Authorization Bypass Through User-Controlled Key.
Which Admidio versions are affected?
Affected versions include releases prior to 5.0.6 across affected packages: admidio/admidio.
What version fixes CVE-2026-30927?
Upgrading to 5.0.6 (or the latest patched release for your respective branch) resolves the vulnerability.
Is admidio/admidio affected?
Yes, admidio/admidio is affected in releases prior to 5.0.6. Upgrade your dependency to 5.0.6 or later.
What is the CVSS score of CVE-2026-30927?
CVE-2026-30927 has a CVSS v3.1 base score of 0.0 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:N.
What CWE is associated with CVE-2026-30927?
CVE-2026-30927 is classified under CWE-639: Authorization Bypass Through User-Controlled Key (The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.).
How can I check Packagist dependencies for CVE-2026-30927?
Run the dependency tree command: 'inspect dependencies for admidio/admidio'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-7pfv-hr63-h7cw",
  "modified" : "2026-03-10T18:39:33Z",
  "published" : "2026-03-09T19:45:20Z",
  "aliases" : [ "CVE-2026-30927" ],
  "summary" : "Admidio: Event participation IDOR - non-leaders can register other users for events via user_uuid parameter",
  "details" : "## Vulnerability\n\nIn `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.\n\nLine 47: `$getUserUuid = admFuncVariableIsValid($_GET, 'user_uuid', 'uuid', ...)`\nLine 424: `if ($event->possibleToParticipate() || $participants->isLeader($gCurrentUserId))`\n\nThe 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.\n\nThe code then operates on `$user->getValue('usr_id')` (the target user from user_uuid) rather than the current user.\n\n## Impact\n- Register unwilling users for events (potential harassment/spam)\n- Cancel other users' event participation\n- Manipulate event participant counts and comments\n- If events have participation limits, fill slots with unwanted registrations\n\n## Fix\nFor non-leader users, force `user_uuid` to the current user:\n```php\nif (!$participants->isLeader($gCurrentUserId)) {\n    $getUserUuid = $gCurrentUser->getValue('usr_uuid');\n}\n```",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:N"
  }, {
    "type" : "CVSS_V4",
    "score" : "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"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "admidio/admidio"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "5.0.6"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/Admidio/admidio/security/advisories/GHSA-7pfv-hr63-h7cw"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-30927"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/Admidio/admidio/issues/1985"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/Admidio/admidio/commit/e47f70cc3cbcdb39635fdbaaef02d19f604b8c3e"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/Admidio/admidio"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-639" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-03-09T19:45:20Z",
    "nvd_published_at" : "2026-03-10T17:40:16Z"
  }
}