Does this website say what the security issue is? Firefox 37 is the most secure Firefox right now, so unless the website is run by security experts who are able to find Firefox exploits before anyone else and didn't report it to us and get paid by our bounty program, then this sounds like the website is wrong.

Can you share the link?

It is www.jodunning.com It doesn't say anything except serious security defect. I imagine they had a problem with someone buying something.

I have a hard time imagining that this site has found a serious security issue. Please continue to use Firefox as normal. I've contact the site and will try to clear this up.

thank you for reporting it!

Another similar thread at https://support.mozilla.org/en-US/questions/1058175

I'm getting the impression it's either something is wrong with their website or I might have some kind of malware. Which do you think? Is version 37.0.1 the latest?

37.0.2 is actually the latest, but you are pretty close :)

Deb100 said

I'm getting the impression it's either something is wrong with their website or I might have some kind of malware. Which do you think? Is version 37.0.1 the latest?

It is the site. The thread I linked to has the same issue with the message targeting Fx 37 users as the host was doing it.