These are security releases.
The 4.0.8 and 4.1.10 (together with 4.1.9) releases fix the following security advisories:
- PowerDNS Security Advisory 2019-04 (CVE-2019-10162)
- PowerDNS Security Advisory 2019-05 (CVE-2019-10163)
The 4.0.8 tarball (signature) and 4.1.10 tarball (signature) are available at downloads.powerdns.com and packages for CentOS 6 and 7, Debian Jessie and Stretch, Ubuntu Trusty, Xenial and Bionic (only for 4.1.10) are available from repo.powerdns.com.