Possible Problem?

Hi guys,a little while ago,I went on the Yahoo website,and got a message from avast that said access to certain Yahoo things had been blocked because the server certificate had been revoked. This didn’t happen when I used Yahoo earlier today,in fact I’ve never gotten that message from avast ever. Now I can’t check my Yahoo mail or do much on the website,is this a problem with Yahoo,or avast? I’m also using the latest version of Mozilla Firefox as well.

No problem here using current versions of Chrome and Avast free.

I am able to read my Yahoo email.

The Yahoo site certificate I see is valid from 4-23-2018 thru 5-19-2018