A theoretical investigation of extraordinary polarized surface waves at the second harmonics of ion and electron cyclotron frequencies propagating across an external steady magnetic field is carried out in the case of weak plasma spatial dispersion when the thermal velocities of plasma particles are much less than the phase velocities of the considered waves. These waves are eigenmodes of a planar plasma–vacuum waveguide structure that is situated in a steady magnetic field oriented parallel to the plasma surface. A cold charged-particle beam is assumed to propagate over the plasma interface. Excitation of surface X modes at the second harmonics of electron and ion cyclotron frequencies due to the beam–plasma interaction is studied analytically. The dependence of surface-type X-mode (STXM) growth rates on the considered waveguide structural parameters is also studied.