Vanecek, who was acquired in a trade with the Washington Capitals on July 8, has allowed three goals on 55 shots in three preseason games.
Tomas Tatar scored his third goal of the preseason for the Devils.
Keith Kinkaid made 19 saves on 20 shots for the Bruins before leaving early in the third period with an undisclosed injury. Kyle Keyser made four saves in relief.
Tatar scored at 10:55 of the first period, receiving a stretch pass from Michael Vukojevic while splitting the defense and deking Kinkaid in front.
