I'm sure some are cultishly devoted to it as are many of Catcher in the Rye's devotees; but is either one a cult novel? I'd also question whether Rousseau's Confessions qualifies.
That said, I'm not sure I know what a cult novel is. When I think of cult fiction I always think of works that a) are science fiction-y or supernatural; b)spout some kind of pseudo-philosophic; and/or c) supposedly "speak to an entire generation" like Kerouac with On The Road. Also, works that inspire hosts of people to dress up like the main characters and quote whole passages to one another.
I've only read 12 of the 50 listed here. How about you?