CertiGhost (CVE-2026-54121) deserves much more attention than it is getting right now, from my point of view.
In a common/default AD CS setup, a low-privileged domain user can create a rogue machine account, trick the CA into issuing a certificate with the identity of a Domain Controller, authenticate as that DC via PKINIT, gain replication access and basically compromise the whole domain.
So if you run on-prem Active Directory with AD CS and your CA is still unpatched, an ordinary domain user may currently have a path to the highest privileges in your domain.
Patch it, obviously, or apply the temporary mitigation. But if you patched only recently, the harder and from my point of view more important question is: did someone already exploit it?
A patch closes the hole. It does not unfuck a domain that was already compromised.
I put a list of things I would check in the first reply.
Overview:
linkedin.com/posts/martinsoh…
Technical details:
gist.github.com/H0j3n/a5ef26…
PoC:
github.com/aniqfakhrul/CVE-2…
Microsoft advisory:
msrc.microsoft.com/update-gu…
Temporary mitigation:
nitter.siddz.com/aniqfakhrul/status/208…