Dupe

A dupe is a person who supports the philosophy, aims or methods of a political party or movement, but does so unknowingly. The term is most often used of people who unknowingly support communist parties in democratic nations, though it has also been applied to ultra-right-wing parties or independence movements.

A dupe is different from a fellow traveller, in that though both are not officially members of a party or movement, the fellow traveller recognizes his/her actions are in support of it, while the dupe does not. For example, a dupe may be asked to take a package to someone as part of their normal work duties, not knowing the package contains classified information and that the recipient has no "need to know" it.