rssh expands command line paramters before invoking chroot. This could result in the disclosure to the client of file names outside of the chroot directory. A posting by the rssh author explains:
The cause of the problem identified by Mr. McCaw is that rssh expanded command-line arguments prior to entering the chroot jail. This bug DOES NOT allow a user to access any of the files outside the jail, but can allow them to discover what files are in a directory which is outside the jail, if their credentials on the server would normally allow them read/execute access in the specified directory.