CyberManufacturing System (CMS) is a vision for manufacturing systems where physical machinery and processes are fully and seamlessly integrated with computational resources. However, this very ubiquitous connectivity opens unintended new doors for cyber-attacks into CMS. This type of attack begins in a digital format, intrudes through computer networks, and ultimately causes physical damages. Despite the criticality of the CMS security, research on the subject is in its infancy. New types of cyber-physical attack are emerging but not well understood. In order to gain new insights into the problems and to assist much needed research, a taxonomy-as a common language for the interdisciplinary work-was developed and is presented in this paper. The taxonomy is defined in six dimensions: (i) human, (ii) product, (iii) equipment, (iv) intellectual property, (v) environment, and (vi) operation. For each dimension, attacks are decomposed further in terms of attack targets, sub-targets and attack methods. Examples of using the taxonomy are presented.