Unfortunately, as of now (October 2019), all Subway cookies have milk and egg ingredients.
For example, their chocolate chip cookies contain nonfat dry milk, natural flavors that contain milk, and eggs.
On top of those, there are controversial ingredients like palm oil, plus ingredients that may or may not be vegan like monoglycerides and sugar.
In short, no Subway Cookies are vegan. I’ll try to keep this page updated if they do release any vegan-friendly cookies in the future.
Similarly, Subway’s veggie patty also isn’t vegan.