  In this paper we examine the stability of scalar perturbations in nonsingular
models which emerge from an interacting vacuum component. The analysis
developed in this paper relies on two phenomenological choices for the energy
exchange between a nonrelativistic fluid and a vacuum component. In both
scenarios it can be shown that closed models may furnish nonsingular orbits of
physical interest in phase space once a decelerated past era is connected to a
graceful exit to late-time acceleration. Regarding such configurations as
background spacetimes we introduce scalar perturbations in order to examine the
stability of these models in a high energy domain. We explicitly show that the
vacuum perturbation is not an independent variable and diverges as dynamics
approaches the bounce. This feature assigns a rather unstable signature to the
dynamics making the choices for the energy transfer ill defined at least for
nonsingular configurations at the bounce scale.
