This page demonstrates the impact of a Subdomain Takeover vulnerability. The attacker does not own the parent domain but is able to host arbitrary content on this trusted subdomain.
Impact:
As an attacker, I can host any content on this subdomain even though
I never purchased or owned the domain.
This may allow:
Attacker Does Not Own Domain
+
Dangling DNS Record
+
Claimable Third-Party Service
=
Subdomain Takeover