Buttons don’t work

No button works in dashboard-posts (add media, choose the tags, switch to text – nothing). I mention that: I changed the theme and turned off all the plugins and nothing worked. I have all the updates. And I tried on three browsers – nothing! Not working. I can’t post my articles.

I contacted my host and got the following answer:
Verifications indicate a problem at WordPress level, a CVE open http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-6389.
Active firewall systems have detected this issue and will not allow access to these links. We recommend open a ticket WordPress and asking them how and when to solve that problem.