The passport order does not spell out in detail the definition of national security. That definition is pretty much the same as it has been since 2003. There are a lot of definitions for national security in various acts—in the CSIS Act, in the security of Canada information sharing act, and so on. Just as is the case for the Investment Canada Act and the Canada Evidence Act, there are a number of other acts that spell out national security as one of the rationales for taking an action, in this case refusing or revoking a passport.
On May 26th, 2015. See this statement in context.