  We consider a Vaidya-type radiating spacetime in Einstein gravity with the
Gauss-Bonnet combination of quadratic curvature terms. Simply generalizing the
known static black hole solutions in Einstein-Gauss-Bonnet gravity, we present
an exact solution in arbitrary dimensions with the energy-momentum tensor given
by a null fluid form. As an application, we derive an evolution equation for
the ``dark radiation'' in the Gauss-Bonnet braneworld.
