{"id":"GHSA-7pfv-hr63-h7cw","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-\u003epossibleToParticipate() || $participants-\u003eisLeader($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 `$user-\u003egetValue('usr_id')` (the target user from user_uuid) rather than the current user.\n\n## Impact\n- Register unwilling users for events (potential harassment/spam)\n- Cancel other users' event participation\n- Manipulate event participant counts and comments\n- If events have participation limits, fill slots with unwanted registrations\n\n## Fix\nFor non-leader users, force `user_uuid` to the current user:\n```php\nif (!$participants-\u003eisLeader($gCurrentUserId)) {\n    $getUserUuid = $gCurrentUser-\u003egetValue('usr_uuid');\n}\n```","aliases":["CVE-2026-30927"],"modified":"2026-03-10T18:48:30.504905Z","published":"2026-03-09T19:45:20Z","database_specific":{"github_reviewed_at":"2026-03-09T19:45:20Z","nvd_published_at":"2026-03-10T17:40:16Z","cwe_ids":["CWE-639"],"severity":"MODERATE","github_reviewed":true},"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"}],"affected":[{"package":{"name":"admidio/admidio","ecosystem":"Packagist","purl":"pkg:composer/admidio/admidio"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.0.6"}]}],"versions":["4.1.0","4.1.3","v4.2-Beta.1","v4.2-Beta.2","v4.2-Beta.3","v4.2.0","v4.2.1","v4.2.10","v4.2.11","v4.2.12","v4.2.13","v4.2.14","v4.2.2","v4.2.3","v4.2.4","v4.2.5","v4.2.6","v4.2.7","v4.2.8","v4.2.9","v4.3-Beta.1","v4.3-Beta.3","v4.3-Beta.4","v4.3-Beta.5","v4.3.0","v4.3.1","v4.3.10","v4.3.11","v4.3.12","v4.3.13","v4.3.14","v4.3.15","v4.3.16","v4.3.17","v4.3.2","v4.3.3","v4.3.4","v4.3.5","v4.3.6","v4.3.7","v4.3.8","v4.3.9","v5.0-Beta.1","v5.0-Beta.2","v5.0-Beta.3","v5.0.0","v5.0.1","v5.0.2","v5.0.3","v5.0.4","v5.0.5"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/03/GHSA-7pfv-hr63-h7cw/GHSA-7pfv-hr63-h7cw.json"}}],"schema_version":"1.9.0","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"}]}