The Firefox password management feature shows alerts about logins that were potentially exposed in data breaches. If it’s likely that one of your saved logins was exposed in a known data breach, you’ll see this alert with its associated login.

How Firefox notifies about website breaches

Firefox checks the date of a known website breach against the date you saved a password for that website. If the website was breached after you saved your password, you’ll see this alert.

Firefox will also check to see if you’ve reused any of these potentially vulnerable passwords with other logins you’ve saved to Firefox. The browser does this by creating an encrypted list of your breached passwords, then checking it against all saved passwords. Firefox does not keep logs of your plaintext passwords or know them.

Turn off website breach alerts

Disabling the feature also prevents Firefox from checking to see if you’ve reused these potentially vulnerable passwords on any of your other saved logins.

1. In the Menu bar at the top of the screen, click Firefox and then select Preferences or Settings, depending on your macOS version.Click the menu button and select Settings.
2. Select the Privacy & Security panel on the left and scroll down to the Logins and PasswordsPasswords section.

   

3. Deselect the checkbox for Show alerts about passwords for breached websites.