The remote Debian host is missing a security-related update.
Multiple vulnerabilities have been discovered in the Xen hypervisor. The Common Vulnerabilities and Exposures project identifies the following problems : - CVE-2015-8338 Julien Grall discovered that Xen on ARM was susceptible to denial of service via long running memory operations. - CVE-2016-4480 Jan Beulich discovered that incorrect page table handling could result in privilege escalation inside a Xen guest instance. - CVE-2016-4962 Wei Liu discovered multiple cases of missing input sanitising in libxl which could result in denial of service. - CVE-2016-5242 Aaron Cornelius discovered that incorrect resource handling on ARM systems could result in denial of service. - CVE-2016-6258 Jeremie Boutoille discovered that incorrect pagetable handling in PV instances could result in guest to host privilege escalation.
Upgrade the xen packages. For the stable distribution (jessie), these problems have been fixed in version 4.4.1-9+deb8u6.