      def mget(*keys)
        options = (keys.pop if keys.last.is_a? Hash) || {}
        if keys.any?
          # Marshalling gets extended before Namespace does, so we need to pass options further
          if singleton_class.ancestors.include? Marshalling
            super(*keys.map {|key| interpolate(key) }, options)
          else
            super(*keys.map {|key| interpolate(key) })
          end
        end
      end
The application deserializes untrusted data without sufficiently verifying that the resulting data will be valid.