ComfyUI v0.23.0 contains a critical unsafe deserialization vulnerability in the LoadTrainingDataset node. Unauthenticated remote attackers can exploit this by uploading a crafted pickle file via the unauthenticated POST /upload/image endpoint. The attacker then queues a workflow graph via POST /prompt referencing the uploaded malicious file. This triggers torch.load to deserialize the attacker-controlled pickle payload using Python's __reduce__ mechanism. The result is arbitrary Python code execution running as the ComfyUI process user. No authentication is required at any stage of the attack chain, making this highly exploitable. A fix has been committed to the ComfyUI GitHub repository.