The maximum capacity at the ground is approximately 100,000, according to its website.
Tickets have been on sale since October 23, and CA said some were still available for the second, third and fourth days of the Test.
CA Executive General Manager Operations Mike McKenna said the sales set the scene for an incredible start to the match.
"It has been fantastic to see the strong demand for tickets to the Ashes Boxing Day Test, with fans eager to catch the cricket action and soak up the great match atmosphere," McKenna said.
"The demand for Day 1 tickets in particular has been impressive and there is a great chance that we will see the world record, for crowd attendance at a single day of cricket, broken on the day."
Australia, who have lost the past three Ashes series, are fighting to reverse a 3-0 defeat in England earlier this year.
The first Test starts in Brisbane on November 21.