One suggestion for anyone concerned about this weakness. You can use the CAA record to pin the domain to a specific certificate authority, issuance method, and account. This is imperfect, as CAA record validation (edit: of CAA extensions) is not mandatory yet. But by March 2027 all the CAs a supposed to have support.
Sprinkle some DNSSEC on the CAA record too, if you'd like.
Just be careful, if you host your DNS at Cloudflare (maybe others?), they will rewrite your CAA record[0] if you use TLS with them. This is in the name of convenience but it was surprising when I first learned.
CAA checking is mandatory, so you can always restrict to a given CA.
To get complete control with DNSSEC, you also need the accounturi and validationmethod extensions (which you need to guarantee only your account can issue, and only with the DNS validation type).
Those aren't yet mandatory, but you can restrict to a CA today which implements them, like Let's Encrypt.
Even without DNSSEC, the CAA record approach can help, as it requires MITMing between the CA and the DNS server, which may be harder in some cases than just MITMing a target site.
If your DNS isn't working, you're not going to be making connections anyway. And if you can't keep DNSSEC running, you can't keep certs up to date either. DNSSEC is actually much simpler, with fewer failure points, once you set it up.
> It is high volume (=it need be cacheable).
It is. Unlike certificates. And the cache lifetimes are much shorter than typical certificate lifetimes.
It is self-evidently not correct that companies that can't keep DNSSEC running can't keep certs running. Entire TLDs have fallen off the Internet because DNSSEC has broken. A certificate never took Slack down for half a day. It's just obviously not true.
It's amazing what practice and investment can do, even for a fragile system like X.509. Yet certs still break constantly. Like permanently killing people's "perpetual" Microsoft Word licenses in a story posted within hours of this one.
Sprinkle some DNSSEC on the CAA record too, if you'd like.