{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 5.8.21"
      },
      "package": {
        "ecosystem": "Packagist",
        "name": "craftcms/cms"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "5.0.0-RC1"
            },
            {
              "fixed": "5.8.22"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 4.16.17"
      },
      "package": {
        "ecosystem": "Packagist",
        "name": "craftcms/cms"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.0.0-RC1"
            },
            {
              "fixed": "4.16.18"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-25498"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-470"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-02-09T20:36:43Z",
    "nvd_published_at": "2026-02-09T20:15:58Z",
    "severity": "HIGH"
  },
  "details": "## Relationship to Previously Patched Vulnerability\n\nThis vulnerability is **in addition to** the RCE vulnerability patched in [GHSA-255j-qw47-wjh5](https://github.com/craftcms/cms/security/advisories/GHSA-255j-qw47-wjh5). That advisory addressed a similar RCE vulnerability that affected two specific routes:\n\n- `/index.php?p=admin%2Factions%2Ffields%2Fapply-layout-element-settings`\n- `/index.php?p=admin%2Factions%2Ffields%2Frender-card-preview`\n\nThis one addresses some additional endpoints that were not covered in the https://github.com/craftcms/cms/security/advisories/GHSA-255j-qw47-wjh5.\n\nThe patched vulnerability used a malicious `AttributeTypecastBehavior` with a wildcard event listener (`\"on *\": \"self::beforeSave\"`) and `__construct()` syntax to trigger RCE via the `typecastBeforeSave` callback. The fix was implemented in commits:\n- [6e608a1](https://github.com/craftcms/cms/commit/6e608a1a5bfb36943f94f584b7548ca542a86fef)\n- [27f5588](https://github.com/craftcms/cms/commit/27f55886098b56c00ddc53b69239c9c9192252c7)\n- [ec43c49](https://github.com/craftcms/cms/commit/ec43c497edde0b2bf2e39a119cded2e55f9fe593)\n\nThis vulnerability follows the same attack pattern (behavior injection via `\"as \u003cbehavior\u003e\"` syntax) but affects a **different code path** (`assembleLayoutFromPost()` in `Fields.php`) that was **not patched** in those commits. The attack vector uses `typecastAfterValidate` instead of `typecastBeforeSave` and does not require the wildcard event listener syntax, demonstrating that multiple entry points exist for this type of vulnerability.\n\n---\n\n## Executive Summary\n\nA Remote Code Execution (RCE) vulnerability exists in Craft CMS where the `assembleLayoutFromPost()` function in `src/services/Fields.php` fails to sanitize user-supplied configuration data before passing it to `Craft::createObject()`. This allows authenticated administrators to inject malicious Yii2 behavior configurations that execute arbitrary system commands on the server. This vulnerability represents an **unpatched variant** of the behavior injection vulnerability addressed in GHSA-255j-qw47-wjh5, affecting different endpoints through a separate code path.\n\n---\n\n## Vulnerability Details\n\n### Attack Prerequisites\n\n- **Authentication:** Admin-level access required\n- **Network Access:** Access to admin panel (`/admin`)\n\n---\n\n\n### Location\n\n- **File:** `src/services/Fields.php`\n- **Function:** `assembleLayoutFromPost()` (lines 1125-1143)\n- **Root Cause:** Missing `cleanseConfig()` call on user-supplied `fieldLayout` POST parameter\n\n### Vulnerable Code Path\n\n```php\n// src/services/Fields.php:1125-1133\npublic function assembleLayoutFromPost(?string $namespace = null): FieldLayout\n{\n    $paramPrefix = $namespace ? rtrim($namespace, \u0027.\u0027) . \u0027.\u0027 : \u0027\u0027;\n    $request = Craft::$app-\u003egetRequest();\n    $config = JsonHelper::decode($request-\u003egetBodyParam(\"{$paramPrefix}fieldLayout\"));\n    // ... additional config values added ...\n    $layout = $this-\u003ecreateLayout($config);  // \u003c-- No cleanseConfig() call!\n    // ...\n}\n\n// src/services/Fields.php:1089-1093\npublic function createLayout(array $config): FieldLayout\n{\n    $config[\u0027class\u0027] = FieldLayout::class;\n    return Craft::createObject($config);  // \u003c-- Untrusted data passed directly\n}\n```\n---\n\n## Attack Chain\n\nThe exploitation leverages Yii2\u0027s object configuration system and behavior attachment mechanism:\n\n1. **Behavior Injection:** Attacker includes `\u0027as rce\u0027` key in the `fieldLayout` JSON POST parameter\n2. **Object Creation:** `Craft::createObject()` processes the config through Yii2\u0027s `BaseYii::configure()`\n3. **Behavior Attachment:** Yii2\u0027s `Component::__set()` detects the `\u0027as \u0027` prefix and attaches the behavior\n4. **RCE Trigger:** When `validate()` is called on the model, `EVENT_AFTER_VALIDATE` fires\n5. **Command Execution:** `AttributeTypecastBehavior` calls the configured typecast function (`ConsoleProcessus::execute`) with the `uid` attribute value as the command\n\n### RCE Gadget Chain\n\n```\nFieldLayout POST parameter\n    \u2192 Craft::createObject()\n    \u2192 Yii2 Component::__set() with \u0027as rce\u0027 key\n    \u2192 AttributeTypecastBehavior attached\n    \u2192 Model::validate() called\n    \u2192 EVENT_AFTER_VALIDATE triggered\n    \u2192 typecastAfterValidate \u2192 typecastAttributes()\n    \u2192 call_user_func([\u0027Psy\\Readline\\Hoa\\ConsoleProcessus\u0027, \u0027execute\u0027], $command)\n    \u2192 Shell command execution\n```\n\n---\n\n## Affected Controllers\n\nThe `assembleLayoutFromPost()` function is called by multiple admin controllers:\n\n| Controller | Action | Permission Required |\n|------------|--------|---------------------|\n| `TagsController` | `actionSaveTagGroup()` | Admin |\n| `CategoriesController` | `actionSaveGroup()` | Admin |\n| `EntryTypesController` | `actionSave()` | Admin |\n| `GlobalsController` | `actionSaveSet()` | Admin |\n| `VolumesController` | `actionSave()` | Admin |\n| `UsersController` | `actionSaveUserFieldLayout()` | Admin |\n| `AddressesController` | `actionSaveAddressFieldLayout()` | Admin |\n\n---\n## References\n\n- https://github.com/craftcms/cms/commit/395c64f0b80b507be1c862a2ec942eaacb353748\n- [GHSA-255j-qw47-wjh5](https://github.com/craftcms/cms/security/advisories/GHSA-255j-qw47-wjh5) - Previously patched RCE vulnerability via behavior injection (affecting different endpoints)\n- [CVE-2024-4990](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-4990) - Related vulnerability that inspired the behavior injection attack pattern\n- [Yii2 GHSA-gcmh-9pjj-7fp4](https://github.com/yiisoft/yii2/security/advisories/GHSA-gcmh-9pjj-7fp4) - Original Yii framework report (framework team declined to fix at framework level)\n\n---",
  "id": "GHSA-7jx7-3846-m7w7",
  "modified": "2026-02-09T22:39:16Z",
  "published": "2026-02-09T20:36:43Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/craftcms/cms/security/advisories/GHSA-7jx7-3846-m7w7"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-25498"
    },
    {
      "type": "WEB",
      "url": "https://github.com/craftcms/cms/commit/395c64f0b80b507be1c862a2ec942eaacb353748"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/craftcms/cms"
    },
    {
      "type": "WEB",
      "url": "https://github.com/craftcms/cms/releases/tag/4.16.18"
    },
    {
      "type": "WEB",
      "url": "https://github.com/craftcms/cms/releases/tag/5.8.22"
    }
  ],
  "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 Vulnerable to potential authenticated Remote Code Execution via malicious attached Behavior"
}