The Twig sandbox mechanism in Craft CMS is configured to allow dangerous functionality from the Yii framework, leading to authenticated RCE in a manner similar to previously disclosed vulnerabilities. The Twig sandbox in Craft CMS works by implementing Twig's `SecurityPolicyInterface`. The resulting `SecurityPolicy` class implements the `checkMethodAllowed` and `checkPropertyAllowed` methods of the interface. The implementations compare whether the called method or property is in a configured a