For discussion on the DigiCert issue that triggered this, have a look at the following HN discussions (which are still active!)
DigiCert's blog post…
DigiCert Revocation Incident (CNAME Domain Validation) (digicert.com) — https://news.ycombinator.com/item?id=41104504 — 136 points by vitaliyf 1 day ago
… and the Bugzilla entry where DigiCert reported this to Mozilla:
Digicert pauses mass certificate revocation due to legal action from customer (bugzilla.mozilla.org) — https://news.ycombinator.com/item?id=41114794 — 9 points by frakkingcylons 23 hours ago