Microsoft has now forced a password reset for accounts for which a match was found.
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 and compared them to a database of over three billion sets of leaked credentials to find 44 million matches.
Microsoft has now forced a password reset for accounts for which a match was found. On the enterprise side, Microsoft will alert the administrator to enforce a credential reset.