Firefox users who visit a website with TLS 1.0 or 1.1 from March 10th will receive an error message. The TLS protocol, which is used for setting up a secure connection, has been in existence for more than 20 years.
All major browser developers have indicated that they will stop supporting TLS 1.0 and 1.1 for security reasons.
These versions of the TLS protocol are, in fact, vulnerable to various attacks such as BEAST, CRIME, and POODLE. Websites that will continue to use these older TLS versions in the future will display an error message in browsers. Mozilla will implement this measure in Firefox 74 on March 10th, 2020.
Only TLS 1.2 or newer will then be accepted for setting up a secure connection between user and website.
For the time being, Firefox will be provided with a button that can be used to remove the block and still connect via TLS 1.0 or 1.1. Eventually, however, the “override button” will disappear from the browser, and support for the older TLS versions will be discontinued altogether. Websites are therefore advised only to use TLS 1.2 or newer.
Google Chrome will also block TLS 1.0 and 1.1 from March onwards. According to Google, 0.25 percent of all web pages loaded by Chrome users will still run via the older TLS versions.
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