An issue has been found in PowerDNS Authoritative Server allowing a remote, authorized master server to cause a high CPU load or even prevent any further updates to any slave zone by sending a large number of NOTIFY messages. Note that only servers configured as slaves are affected by this issue.
This issue has been assigned CVE-2019-10163.
PowerDNS Authoritative up to and including 4.1.8 is affected. Please note that at the time of writing, PowerDNS Authoritative 3.4 and below are no longer supported, as described in https://doc.powerdns.com/authoritative/appendices/EOL.html.
We would like to thank George Asenov for finding and subsequently reporting this issue!