As mentioned previously, please can you keep the language family friendly. I appreciate that people are concerned, but let's try to be civil about it before anyone has to be removed.

There are no plans to include this fix in versions of Firefox going back to 2017. This is the same stance taken for other security and stability fixed - you are best using the latest version of Firefox or at least the latest ESR version.

I do appreciate that you may be using older versions of operating systems that Firefox is not available for and that (certainly in the case of Apple hardware) it is not easy or low cost to replace. It is very likely that in these instances that your operating system is no longer receiving important security updates so while I do appreciate that you are concerned about Firefox, you really need to consider carefully updating your device.

i'm NOT asking for an "official" fix, i'm asking for an UNOFFICIAL HACK, maybe someone in community may be able to provide to keep firefox 56 (win7) and firefox 90 (linux mint) alive!

i know mozilla won't do anything for its users, mozilla always makes worst decisions AGAINST its users; this user hostile company had to introduce this now breaking certificate shenanigans in the first place - noone needs this idiocy! no wonder that firefox is losing more and more users!!!

and as i already mentioned in this thread: i RELY on firefox 56 (win7) due to addons not working anymore in later versions and i RELY on firefox 90 on linux mint as this is the LAST VERSION allowing me to disable that ugly proton cretinism mozilla had to shove down our throats!

thus i repeat: i will NOT, NEVER, NEVER EVER "update" (=DOWNGRADE) any of my firefox installations!!!

and which date is now true? january 14 as message in firefox 90 showed or march 14 mentioned here?

January 14 is when you will start to have some issues if using old versions, though that has not been the most clear as to what. It is March 14 when things like Extensions and such may stop working as explained in https://support.mozilla.org/en-US/kb/root-certificate-expiration

Mozilla has been quite good with supporting Firefox users with old eol OS's. For example they supported the then eol WinXP/Vista for over two years past when Chrome/Chromium based browsers dropped. At present they are still supporting the eol Windows 7, 8, 8.1 (and macOS 10.12, 10.13, 10.14) even though Chrome/Chromium based browsers dropped Windows 7, 8, 8.1 way back in Jan/Feb 2023.

They cannot be expected to support old OS's and old Firefox versions forever as things have to give as things progress on.

Which are the add-ons that you rely on?

one important example is chatzilla, which isn't supported in ff57 and newer since mozilla decided to make addons less powerful. i already mentioned that. other important addons not working due to these restrictions are all-in-one-gestures (mouse gestures which literally work everywhere, also in setting tabs, etc.) and glassmyfox, which making firefox look like aero theme in windows 7 just to name some extensions.

and i also use firefox 56 for downloading ftp stuff (like software for good old amiga os and ms dos which still is offered via ftp. ftp support also was removed in later versions of firefox.