Opera revealed that early last week the company detected a possible security breach on the server of its cloud sync service, forcing a password reset for the 1.7 million users possibly affected by the hack.

Opera has encryption in place to protect the passwords stored in the system, but the company is understandably not taking any chances.

In the blog post announcing the incident, Opera said that while the attack was quickly blocked, the company has launched an investigation into the matter, as it believes that the account information and passwords of some of the service's users may have been compromised.

The company added that it has sent an e-mail to all users of the browser's sync service and asked them to change their passwords. Without reading the e-mail though, users would have noticed that something was wrong as they would have seen the forced password reset.

As a precaution, Opera has also advised users to change the password for the third-party websites they have synchronized with the service. It would also be a good idea to change the passwords for the accounts of users who utilize the same log-in credentials as the one they used for the Opera service.

The company confirmed that the passwords for its sync service are hashed and salted — a standard practice in the industry — that scrambles the passwords so that they are unusable if obtained in a security breach. However, Opera did not reveal any specific detail on how the passwords are scrambled, and if the attackers would have the ability to unscramble them.

While the 1.7 million users possibly affected by the security breach is a small percentage of the total number of users of the Opera browser, which currently stands at around 350 million people, Opera has still issued a sincere apology for the inconvenience that the security breach has caused.

Earlier in the year, Opera integrated a free virtual private network, or VPN, right into its desktop browser, which is a move that enhanced the online privacy of users by allowing them to easily switch to a 256-bit encrypted connection that hides their details.

Opera became the first major internet browser to integrate a free and unlimited VPN into its software, eliminating the need for users to install VPN extensions or purchase VPN subscriptions.

It has since also launched a VPN app for iOS and Android devices. The app is completely free and offers mobile device users with unlimited VPN usage.