  In this paper we study the global exponential stability in the $L^{2}$ norm
of semilinear $1$-$d$ hyperbolic systems on a bounded domain, when the source
term and the nonlinear boundary conditions are Lipschitz. We exhibit two
sufficient stability conditions: an internal condition and a boundary
condition. This result holds also when the source term is nonlocal. Finally, we
show its robustness by extending it to global Input-to State Stability in the
$L^{2}$ norm with respect to both interior and boundary disturbances.
