Wrong. The Packers' 12 NFL Championships are the league record. Da Bears have 9 NFL Championships, and one Super Bowl. I shouldn't go on but I can't help myself. The Packers' 24-12 post-season mark is the best of all-time, and the Green and Gold is also the only team in the league to win 3 consecutive championships, and they did it twice - '29-'31 and '65-67. Finally, since '92, '93, '94, '95, '96, and '97, the Packers have the best record in the NFL.
The Packers' legacy in professional football is matched only by the Yankees in baseball and Celtics in basketball.
I'm going to give the Cowboys an 5-5 NFL Championship record, having lost to the Packers in 1966 and 1967 when the Super Bowl was a AFL-NFL matchup. So, certainly, the five losses put the Cowboys into rarefied air.