Craft CMS is a content management system (CMS). From version 5.6.0 to before version 5.9.11, in src/controllers/EntryTypesController.php, the $settings array from parse_str is passed directly to Craft::configure() without Component::cleanseConfig(). This allows injecting Yii2 behavior/event handlers via as or on prefixed keys, the same attack vector as the original advisory. Craft control panel administrator permissions and allowAdminChanges must be enabled for this to work. This issue has been patched in version 5.9.11.
Weakness
The product uses external input with reflection to select which classes or code to use, but it does not sufficiently prevent the input from selecting improper classes or code.