The remote Debian host is missing a security-related update.
Several vulnerabilities were discovered in Libvirt, a virtualisation abstraction library : - CVE-2018-1064 Daniel Berrange discovered that the QEMU guest agent performed insufficient validation of incoming data, which allows a privileged user in the guest to exhaust resources on the virtualisation host, resulting in denial of service. - CVE-2018-5748 Daniel Berrange and Peter Krempa discovered that the QEMU monitor was susceptible to denial of service by memory exhaustion. This was already fixed in Debian stretch and only affects Debian jessie. - CVE-2018-6764 Pedro Sampaio discovered that LXC containers detected the hostname insecurely. This only affects Debian stretch.
Upgrade the libvirt packages. For the oldstable distribution (jessie), these problems have been fixed in version 1.2.9-9+deb8u5. For the stable distribution (stretch), these problems have been fixed in version 3.0.0-4+deb9u3.