Due to one add-on not being compatible with newer Firefox versions (57 and up), I'm stuck with Firefox 56 (running on Debian) for a while.
I'm OK with things like performance or looks not being the best you can get. However, I am worried about security issues and wonder how dangerous it is.
Should I choose Firefox 52 ESR instead of the Firefox 56?
The versions and security fixes are listed here: https://www.mozilla.org/en-US/security/known-vulnerabilities/firefox/
While it is not recommended to run older versions with known issues, one way you might be able to get along is to run the old Firefox in a container or virtual machine in order to get some protection for your personal data on your host.
