{
  "affected": [
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "craftcms/cms"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "5.0.0-RC1"
            },
            {
              "fixed": "5.10.6"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [],
  "database_specific": {
    "cwe_ids": [
      "CWE-863"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-08-06T21:43:54Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "A control-panel user who holds only the viewCategories permission for a category group (and not saveCategories) can permanently modify that group\u0027s category structure \u2014 reordering and re-parenting categories via the structures/move-element action.\n\nA read-time authorization grant that a write endpoint later trusts. For categories, the structureEditable flag is computed from the view permission (`src/elements/Category.php:205`) instead of the save permission (entries correctly use saveEntries \u2014 `src/elements/Entry.php:341`). When the read-only category index renders, `craft\\base\\Element::indexHtml()` calls `Craft::$app-\u003egetSession()-\u003eauthorize(\u0027editStructure:\u003cstructureId\u003e\u0027);` StructuresController then authorizes the structure-mutating action solely on that session grant, with no canSave re-check.\n\nVerified on Craft CMS 5.10.5. Same class as the moderate-severity authorization bypasses fixed in 5.10.3 and 5.10.5; this is a distinct, unpatched instance.\n\n## Impact\n\nA low-privileged, authenticated user (view-only on a category group) can persistently alter the sibling ordering and parent/child nesting of the category taxonomy. Because a category\u2019s URI is derived from its position in the structure (ancestor slugs), moving a category changes its URL and the URLs of its descendants, and can corrupt any navigation/menus built from the category tree. This is an integrity/broken access-control issue: content that the user has no permission to modify is being modified. No confidentiality impact and no RCE; scope is content/taxonomy integrity.",
  "id": "GHSA-xxpx-f366-4xpq",
  "modified": "2026-08-07T17:01:06Z",
  "published": "2026-08-06T21:43:54Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/craftcms/cms/security/advisories/GHSA-xxpx-f366-4xpq"
    },
    {
      "type": "WEB",
      "url": "https://github.com/craftcms/cms/commit/eb63721b8476ef53f21d7de53d156eef531cb57d"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/craftcms/cms"
    },
    {
      "type": "WEB",
      "url": "https://github.com/craftcms/cms/releases/tag/4.18.2"
    },
    {
      "type": "WEB",
      "url": "https://github.com/craftcms/cms/releases/tag/5.10.6"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Craft CMS:Authorization bypass: view-only Categories user can modify category structure via structures/move-element"
}