Chrome and firefox no longer accept certificates that rely on the NSA's "SHA-1" or "secure hash algorithm #1" as that cipher is no longer believed to be trustworthy. SHA256, which is the same method only with a much larger key, is the new shiny.
In my opinion, you should not be deeply concerned, unless you see this warning on a banking or shopping website, or if you're using the same passwords that you use on a banking or shopping site.
People with less advanced browsers will not see this warning. And yes, I'm grossly oversimplifying, but there's no need to go any further down the rabbit hole!
--Charlie
_______________________________________________
Elec-trak mailing list
Elec-trak cosmos phy tufts edu
https://cosmos.phy.tufts.edu/mailman/listinfo/elec-trak