A rogue primary server may cause file descriptor exhaustion and eventually a denial of service, when a PowerDNS secondary server forwards a DNS update request to it.
Exploitability
AV:NAC:HPR:NUI:NScope
S:UImpact
C:NI:NA:H5.9/CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H