The vulnerability allowed Remote Code Execution because Apache IoTDB did not validate the URI from which User Defined Functions (UDFs), Triggers, PipePlugins, or AI Models could be loaded. An attacker with privileges to create these entities could specify a URI pointing to a malicious JAR file. The identified vulnerable functions are visitor methods within the query execution plan generation phase. These methods are responsible for handling CREATE FUNCTION, CREATE TRIGGER, CREATE PIPEPLUGIN, and CREATE MODEL statements. Before the patch, these methods would directly proceed to create tasks for loading resources from the provided URI without any validation. The patch introduced checks in these visitor methods using ExecutableManager.isUriTrusted (which itself relies on a new configuration trusted_uri_pattern) to ensure that URIs are matched against a trusted pattern before proceeding. Therefore, these visitor methods, in their pre-patch state, contained the vulnerability as they lacked the necessary URI validation, enabling the RCE.