A winglet linked to a wing of an aircraft and equipped with a configuration changing device, the winglet being configured to be deformed elastically between a first configuration in the absence of an activation loading and a second configuration in the presence of an activation loading. The configuration changing device comprises at least one blocking cable configured to hold the winglet in the second configuration and at least one blocking system which comprises a tank containing a material configured to occupy a solid state in which the material immobilizes the blocking cable and a liquid state in which the material does not immobilize the blocking cable and allows the displacement thereof. An aircraft comprises wings provided with the winglets.