Yahoo! has said that around 4.5 lakh user accounts and password details were hacked on Wednesday.
"We confirm that an older file from Yahoo! Contributor Network (previously Associated Content) containing approximately 450,000 Yahoo! and other company users names and passwords was compromised on July 11," Yahoo! said in a statement.
The company, which has 29.8 crore users worldwide, noted that less than 5 per cent of the Yahoo! accounts information leaked had valid passwords.
However, it could not be ascertained whether accounts from India were affected.
"We are taking immediate action by fixing the vulnerability that led to the disclosure of this data, changing the passwords of the affected Yahoo! users and notifying the companies whose users accounts may have been compromised," the company added.
According to media reports published yesterday, a hacking group which called itself the D33Ds Company claimed to had penetrated the Yahoo sub-domain using what's known as a union-based SQL injection and posted the user information on a public website.
Yahoo! said that users should change their passwords on a regular basis.
