The Cardiff striker sustained a grade two tear to his hamstring in Saturday's draw with Blackpool.
The injury will keep him out for anything between three and eight weeks which makes the September 5 game against Macedonia almost impossible and the Dutch match four days later unlikely.
"I think it pretty much rules me out of the next Scotland games now," McCormack told the Scottish Sun on his 22nd birthday.
"It'll be difficult watching the lads playing in the games but hopefully they can get the results we need.
"I knew I'd done my hamstring as soon as I overstretched.
"I'm so disappointed about it but I'm going to take my time with things.
"I had this injury with my other hamstring last season and you've got to be careful.
"I'll work hard and hopefully come back as quickly as I can but I won't come back earlier than I should.
"It's hard that I can't do well for Cardiff or Scotland for the next few weeks.
"I'd been playing well so far this season.
"For the first game I was on the left of midfield and did really well. Then against Blackpool I was just off the front two and it was going good."