Admidio before 5.0.17 Event Guest Restriction Bypass via events_function.php

{
  "id": "38133e88ae8e695260c3cdcf865bb9d1e9feff0c4758929dc9bd69a03fcdb88e",
  "url": "https://www.cve.org/CVERecord?id=CVE-2026-117554",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Admidio before 5.0.17 Event Guest Restriction Bypass via events_function.php",
    "summary": "Admidio before 5.0.17 contains an improper access control vulnerability that allows authenticated members to register event guests by submitting the additional_guests field when guests are disallowed. Attackers can set additional_guests to the remaining seat count in modules/events/events_function.php to exhaust event capacity and block other members from registering.",
    "evidence": "cve:CVE-2026-117554",
    "products": [
      {
        "name": {
          "value": "admidio",
          "evidence": "/containers/cna/affected/0/product"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-117554",
      "aliases": [
        "CVE-2026-117554"
      ],
      "metrics": [
        {
          "format": "CVSS",
          "cvssV4_0": {
            "version": "4.0",
            "baseScore": 5.3,
            "attackVector": "NETWORK",
            "baseSeverity": "MEDIUM",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N",
            "userInteraction": "NONE",
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "privilegesRequired": "LOW",
            "subIntegrityImpact": "NONE",
            "vulnIntegrityImpact": "LOW",
            "subAvailabilityImpact": "NONE",
            "vulnAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "vulnConfidentialityImpact": "NONE"
          }
        },
        {
          "format": "CVSS",
          "cvssV3_1": {
            "scope": "UNCHANGED",
            "version": "3.1",
            "baseScore": 4.3,
            "attackVector": "NETWORK",
            "baseSeverity": "MEDIUM",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N",
            "integrityImpact": "LOW",
            "userInteraction": "NONE",
            "attackComplexity": "LOW",
            "availabilityImpact": "NONE",
            "privilegesRequired": "LOW",
            "confidentialityImpact": "NONE"
          }
        }
      ],
      "affected": [
        {
          "vendor": "admidio",
          "product": "admidio",
          "versions": [
            {
              "status": "affected",
              "version": "0",
              "lessThan": "5.0.17",
              "versionType": "semver"
            }
          ],
          "packageURL": "pkg:composer/admidio/admidio",
          "defaultStatus": "unaffected"
        }
      ],
      "modified": "2026-10-27T13:07:50.357Z",
      "provider": "cve",
      "references": [
        "https://github.com/Admidio/admidio/issues/2231",
        "https://github.com/Admidio/admidio",
        "https://github.com/Admidio/admidio/security/advisories/GHSA-92g9-59rr-c3qg",
        "https://github.com/Admidio/admidio/commit/5b0ee3585d2a69a6e85fee00b7b93f3ebc1e44d9",
        "https://github.com/Admidio/admidio/releases/tag/v5.0.17",
        "https://github.com/Admidio/admidio/blob/v5.0.16/modules/events/events_function.php#L446-L462",
        "https://www.vulncheck.com/advisories/admidio-before-5.0.17-event-guest-restriction-bypass-via-events-function-php"
      ],
      "provider_metadata": {
        "cna": {
          "orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
          "shortName": "VulnCheck",
          "dateUpdated": "2026-10-27T13:07:50.357Z"
        }
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-117554",
        "evidence": "/cveMetadata/cveId"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/containers/cna/metrics"
  },
  "source_id": "core-cve",
  "document_id": 392682,
  "published_at": "2026-10-27T13:07:50.357+00:00"
}