Cummins returned home early from Australia A's tour of South Africa with the back injury last week, with sans on Monday confirming the worst.
"Pat returned home early from the Australia A tour of Africa with some side/back soreness and scans have shown a partial recurrence of his lower back bone stress injury suffered in October last year when he returned home from Champions League," Cricket Australia Chief Medical Officer Justin Paoloni said.
"He will be closely monitored to determine his return to the playing field, but expect that he will miss most of the 2013-14 domestic cricket season."
It is a worrying sign for the rising 20-year-old fast bowler, who has missed the last two domestic summers with back and foot injuries.
Cummins hasn't featured for Australia since his remarkable Test debut in 2011.
He burst onto the Test scene with a man-of-the-match performance against South Africa in Johannesburg in November that year, claiming 6-79 in the second innings and hitting the winning runs in a narrow Australian victory.
He was also sent home from Australia's one-day tour of England in the middle of last year with a side strain.
Cummins has made just six first-class appearances in three years due to his long list of injuries.