  We present new regular solutions of Einstein-charged scalar field theory in a
cavity. The system is enclosed inside a reflecting mirror-like boundary, on
which the scalar field vanishes. The mirror is placed at the zero of the scalar
field closest to the origin, and inside this boundary our solutions are
regular. We study the stability of these solitons under linear, spherically
symmetric perturbations of the metric, scalar and electromagnetic fields. If
the radius of the mirror is sufficiently large, we present numerical evidence
for the stability of the solitons. For small mirror radius, some of the
solitons are unstable. We discuss the physical interpretation of this
instability.
