A Remote Code Execution (RCE) vulnerability exists in Craft CMS where the `assembleLayoutFromPost()` function in `src/services/Fields.php` does not properly sanitize user-supplied configuration data before passing it to `Craft::createObject()`. This allows authenticated administrators to inject malicious Yii2 behavior configurations, potentially executing arbitrary system commands on the server. This is an unpatched variant of a behavior injection issue previously addressed in a different set of endpoints. The vulnerability is located in the `assembleLayoutFromPost()` function, specifically lines 1125-1143 of the `src/services/Fields.php` file, due to a missing call to `cleanseConfig()` on the `fieldLayout` POST parameter. The attack involves injecting a behavior using the 'as rce' key in the `fieldLayout` JSON POST parameter, which then triggers command execution when the model is validated. The vulnerability affects multiple admin controllers, including `TagsController`, `CategoriesController`, `EntryTypesController`, `GlobalsController`, `VolumesController`, `UsersController`, and `AddressesController`.