CVE-2026-33157: Craftcms/cms Remote Code Execution Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-2fph-6v5w-89hh",
  "modified" : "2026-03-25T20:59:38Z",
  "published" : "2026-03-24T16:50:42Z",
  "aliases" : [ "CVE-2026-33157" ],
  "summary" : "Craft CMS is Vulnerable to Authenticated Remote Code Execution via Malicious Attached Behavior",
  "details" : "## Summary\n\nA Remote Code Execution (RCE) vulnerability exists in Craft CMS 5.x and 4.x that bypasses the security fixes for GHSA-7jx7-3846-m7w7 and GHSA-255j-qw47-wjh5. This vulnerability can be exploited by any authenticated user with control panel access.\n\nThe existing patches add `cleanseConfig()` to `assembleLayoutFromPost()` and various `FieldsController` actions to strip Yii2 behavior/event injection keys (`as ` and `on ` prefixed keys). However, the `fieldLayouts` parameter in `ElementIndexesController::actionFilterHud()` is passed directly to `FieldLayout::createFromConfig()` without any sanitization, enabling the same behavior injection attack chain.\n\n## Impact\n\n- **Attack Type**: Remote Code Execution (RCE)\n- **Authentication Required**: Authenticated user with control panel access (`accessCp` permission)\n\n## Vulnerability Details\n\n### Root Cause\n\nIn `ElementIndexesController::actionFilterHud()` (line 493-494), the `fieldLayouts` body parameter is passed to `FieldLayout::createFromConfig()` without `cleanseConfig()`:\n\n```php\n// ElementIndexesController.php:485-494\nif ($conditionConfig) {\n    $conditionConfig = Component::cleanseConfig($conditionConfig); // conditionConfig IS cleansed\n    $condition = $conditionsService->createCondition($conditionConfig);\n} else {\n    $condition = $this->elementType()::createCondition();\n}\n\nif (!empty($fieldLayouts)) {\n    // fieldLayouts is NOT cleansed!\n    $condition->setFieldLayouts(array_map(\n        fn(array $config) => FieldLayout::createFromConfig($config),\n        $fieldLayouts\n    ));\n}\n```\n\nNote the inconsistency: `conditionConfig` is sanitized with `cleanseConfig()`, but `fieldLayouts` is not.\n\n### Attack Chain\n\n1. Send a `fieldLayouts` array containing config with `\"as <name>\"` prefixed keys\n2. `FieldLayout::createFromConfig($config)` -> `new self($config)` -> `Model::__construct($config)`\n3. `App::configure($this, $config)` processes each key\n4. `\"as rce\"` key -> `Component::__set(\"as rce\", $value)` -> `Yii::createObject($value)` -> instantiates `AttributeTypecastBehavior` and attaches it to the FieldLayout\n5. `\"on *\"` key -> registers a wildcard event handler\n6. `parent::__construct()` -> `init()` -> `setTabs([])` -> `getAvailableNativeFields()` -> `trigger(EVENT_DEFINE_NATIVE_FIELDS)`\n7. The wildcard handler fires -> `AttributeTypecastBehavior::beforeSave()` -> `typecastAttributes()`\n8. `$this->owner->typecastBeforeSave` -> resolved via `Component::__get()` -> returns the command string from the behavior's own property\n9. `call_user_func([ConsoleProcessus::class, 'execute'], $command)` -> `shell_exec($command)`\n\n### Prerequisites\n\n- A user account with control panel access",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "craftcms/cms"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "5.6.0"
      }, {
        "fixed" : "5.9.13"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 5.9.12"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/craftcms/cms/security/advisories/GHSA-2fph-6v5w-89hh"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-33157"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/craftcms/cms/commit/97e90b4bdee369c1af3ca77a77531132df240e4e"
  }, {
    "type" : "ADVISORY",
    "url" : "https://github.com/advisories/GHSA-255j-qw47-wjh5"
  }, {
    "type" : "ADVISORY",
    "url" : "https://github.com/advisories/GHSA-7jx7-3846-m7w7"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/craftcms/cms"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/craftcms/cms/releases/tag/5.9.13"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-470" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-03-24T16:50:42Z",
    "nvd_published_at" : "2026-03-24T18:16:09Z"
  }
}