The 25-year-old Swede made his NHL debut on Oct. 6 against the Calgary Flames, stopping 32 shots for his first career victory.
In five appearances this season, Lack has a 2-2-0 record and .911 save percentage behind Canucks' No. 1 goalie Roberto Luongo.
Prior to this year, Lack played three seasons with the Canucks' American Hockey League affiliates.
The six-foot-five, 196-pound goaltender was originally signed by Vancouver as a free agent on April 6, 2010, and could have become a restricted free agent this summer.