transitions occurring in systems amenable to be described by Langevin equations including a multiplicative noise (MN) term are the subject of current intense studies. This embraces a broad variety of systems both in physics and in other disciplines. A phenomenology much richer and complex than that appearing in equilibrium systems, including counterintuitive behaviors, has been reported to appear in these, typically non-equilibrium, situations. See [@Review; @Sancho] for detailed introductions to this growing field, including many different realizations.

The interest in MN problems is enlarged even further, because of the existing mappings between them and other prototypical non-equilibrium problems [@Review]. A well known instance is the Kardar-Parisi-Zhang (KPZ) equation, describing the kinetic roughening transition of generic interfaces under non-equilibrium conditions [@KPZ; @Barabasi; @HZ], which can be mapped onto a MN Langevin equation, by performing the so called Cole-Hopf transformation linking the interface height at each point with the activity field of the MN equation. If an interface under consideration is described by the KPZ equation and it is physically limited by a wall, [*i.e.*]{} if the heights cannot be larger of smaller than a certain value, then this problem, [*bounded KPZ*]{}, can be mapped into a multiplicative noise equation by employing 