The remote Debian host is missing a security-related update.
Multiple vulnerabilities have been discovered in the Xen hypervisor : - CVE-2018-8897 Andy Lutomirski and Nick Peterson discovered that incorrect handling of debug exceptions could result in privilege escalation. - CVE-2018-10471 An error was discovered in the mitigations against Meltdown which could result in denial of service. - CVE-2018-10472 Anthony Perard discovered that incorrect parsing of CDROM images can result in information disclosure. - CVE-2018-10981 Jan Beulich discovered that malformed device models could result in denial of service. - CVE-2018-10982 Roger Pau Monne discovered that incorrect handling of high precision event timers could result in denial of service and potentially privilege escalation.
Upgrade the xen packages. For the stable distribution (stretch), these problems have been fixed in version 4.8.3+xsa262+shim4.10.0+comet3-1+deb9u6.