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

{
  "id": "615e8c9303c67bb9f5f97c3c89df7f9e497d676d5b8dc1757d344afd8b64aaf3",
  "url": "https://osv.dev/vulnerability/CVE-2026-30927",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Admidio: Event participation IDOR - non-leaders can register other users for events via user_uuid parameter",
    "summary": "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.",
    "evidence": "osv:CVE-2026-30927",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-30927",
      "aliases": [
        "CVE-2026-30927",
        "GHSA-7pfv-hr63-h7cw"
      ],
      "metrics": [
        {
          "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": [
        {
          "ranges": [
            {
              "repo": "https://github.com/admidio/admidio",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "e11799f647188263196de4acacf80c9a5ad32b91"
                },
                {
                  "fixed": "e47f70cc3cbcdb39635fdbaaef02d19f604b8c3e"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:admidio:admidio:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "5.0.6"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "range": [
                      {
                        "fixed": "e47f70cc3cbcdb39635fdbaaef02d19f604b8c3e"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v5.0.5",
            "v5.0.4",
            "v34",
            "v5.0.3",
            "v5.0.2",
            "v5.0.1",
            "v5.0.0",
            "v5.0-Beta.3",
            "v5.0-Beta.2",
            "v5.0-Beta.1",
            "v4.3-Beta.1",
            "v4.1-Beta.2",
            "v4.0-Beta.1",
            "v3.2-Beta.1",
            "v3.1.5",
            "v3.0.6",
            "3.0-Beta.3",
            "3.0-Beta.1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-30927.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:28.932817108Z",
      "provider": "osv",
      "references": [
        "https://github.com/Admidio/admidio/security/advisories/GHSA-7pfv-hr63-h7cw",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/30xxx/CVE-2026-30927.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-30927",
        "https://github.com/Admidio/admidio/issues/1985",
        "https://github.com/Admidio/admidio/commit/e47f70cc3cbcdb39635fdbaaef02d19f604b8c3e"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-639"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/30xxx/CVE-2026-30927.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-30927",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 495609,
  "published_at": "2026-03-09T23:03:55.824+00:00"
}