We recently discovered a pattern of suspicious logins to Firefox Accounts. It appears that an attacker with access to passwords from data breaches at other websites has been attempting to use those passwords to log into users’ Firefox Accounts. In some cases where a user reused their Firefox Accounts password on another website and that website was breached, the attacker was able to take the password from the breach and use it to log into the user’s Firefox Account.

We’ve already taken steps to protect our users. We automatically reset the passwords of users whose accounts were broken into. We also notified these users with instructions on how to regain access to their accounts and further protect themselves going forward. This investigation is ongoing and we will notify users if we discover unauthorized activity on their account.

User security is paramount to us. It is part of our mission to help build an Internet that truly puts people first and where individuals are empowered, safe and independent. Events like this are a good reminder of the importance of good password hygiene. Using strong and different passwords across websites is important for staying safe online. We’re also working on additional rate-limiting and other security mechanisms to provide additional protection for our users.