{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 5.9.13"
      },
      "package": {
        "ecosystem": "Packagist",
        "name": "craftcms/cms"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "5.5.0"
            },
            {
              "fixed": "5.9.14"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [],
  "database_specific": {
    "cwe_ids": [
      "CWE-94"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-09T13:44:12Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "The `actionRenderCardPreview()` method in `FieldsController` passes the `fieldLayoutConfig` POST parameter directly to `Fields::createLayout()` without calling `Component::cleanseConfig()`. This allows Yii2 event handler injection via `on eventName` keys in the config array, leading to arbitrary code execution.\n\nThis is the same vulnerability pattern that was fixed in GHSA-4484-8v2f-5748 (same file, `_fldComponent` method correctly uses `cleanseConfig`), GHSA-qx2q-q59v-wf3j (EntryTypesController), and GHSA-2fph-6v5w-89hh (ElementIndexesController).\n\n## PoC\n\nAs an admin user with a valid session:\n\n```\nPOST /admin/actions/fields/render-card-preview HTTP/1.1\nContent-Type: application/x-www-form-urlencoded\nCookie: CraftSessionId=\u003csession\u003e\n\nfieldLayoutConfig[on+init]=phpinfo\u0026CRAFT_CSRF_TOKEN=\u003ctoken\u003e\n```\n\nWhen the FieldLayout object is constructed, Yii2 processes the `on init` key as an event handler registration. During `Component::init()`, the `init` event is triggered, calling `phpinfo()`. The phpinfo output (which includes environment variables, potentially containing database credentials and `CRAFT_SECURITY_KEY`) will appear in the response.\n\n## Impact\n\nAn authenticated admin can achieve RCE through Yii2 event handler injection. While this requires admin access (same as GHSA-4484-8v2f-5748, which was rated moderate), it allows arbitrary PHP function execution and information disclosure via phpinfo.",
  "id": "GHSA-86vw-x4ww-x467",
  "modified": "2026-07-09T13:44:12Z",
  "published": "2026-07-09T13:44:12Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/craftcms/cms/security/advisories/GHSA-86vw-x4ww-x467"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/craftcms/cms"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Craft CMS: RCE via missing cleanseConfig in FieldsController::actionRenderCardPreview"
}