Football Australia on Thursday said it was investigating a possible cybersecurity flaw that may have accidentally exposed players' contracts and passport pages, and sensitive data on fans.
The sport's governing body said it had launched an internal probe after reports said it had left the digital keys to access sensitive information buried in website HTML code.
"Football Australia is aware of reports of a possible data breach and is investigating the matter as a priority," it said in a statement.
"Football Australia takes the security of all its stakeholders seriously" it added.
"We will keep our stakeholders updated as we establish more details."
The website Cybernews said it had discovered the problem which could have exposed data on players and every customer or fan of Football Australia.
Cybernews said Football Australia had fixed the problem after they were informed, but it was not clear if the data had been accessed by any malicious actors.