Microsoft emailed an unknown number of users April 12 across its Outlook, MSN and Hotmail platforms alerting them of a data breach that occurred between Jan. 1 and March 28, according to Wired.
In the email, Microsoft warned users that hackers had used a set of stolen credentials for a customer support platform to gain access to email addresses in messages, message subject lines and folder names inside accounts, according to the report.
Microsoft extended the severity of the breach April 14, alerting users that hackers also gained access to the text of messages and attachments of 6 percent of those who received an initial notification from the company.
The company had previously denied that full emails were affected to TechCrunch.
Microsoft has since disabled the compromised credentials and blocked the hackers' access. The company has also increased threat monitoring for accounts that were affected "out of an abundance of caution," a Microsoft spokesperson told Wired.