The latest version of Firefox addresses at least twenty-four security vulnerabilities and changes the way non-encrypted sites appear in the address bar.
As usual, there’s nothing like a proper announcement for Firefox 51. What we get from Mozilla instead is a blog post that discusses some new features in Firefox, and mentions the new version number almost accidentally in the third paragraph. Once again, CERT does a better job of announcing the new version than Mozilla.
Starting with version 51, Firefox will flag sites that are not secured with HTTPS if they prompt for user passwords. Secure sites will show a green lock at the left end of the address bar as before, but sites that are not secure will show a grey lock with a red line through it. Previously, non-encrypted sites showed no lock icon at all. The idea is to draw the user’s attention to the fact that they are browsing without the security of encryption, which is risky when sensitive information (passwords, credit card numbers) is entered by the user.