Daniel P. Berrange reported that Libvirt, a virtualisation abstraction library, does not properly handle the default_tls_x509_verify parameters in qemu.conf when setting up TLS clients and servers in QEMU, resulting in TLS clients for character devices and disk devices having verification turned off and ignoring any errors while validating the server certificate. More informations in https://security.libvirt.org/2017/0002.html .