Ie, if / has to be encoded as %2f the traversal should use `..%2f..%2f..%2fetc%2fpasswd` not `..%2f..%2f../etc/passwd`
Ie, if / has to be encoded as %2f the traversal should use
..%2f..%2f..%2fetc%2fpasswdnot..%2f..%2f../etc/passwd