Microsoft's threat research team scanned all accounts between January and March this year.
In a major security issue, 44 million Microsoft accounts were discovered using breached user names and passwords.
As PC Mag reports, Microsoft's threat research team scanned all accounts between January and March this year.
The software giant then compared the accounts to a database of over 3 billion sets of leaked credentials and find 44 million matches.
Microsoft has now forced a password reset for accounts for which a match was found.