The remote host is missing an update to xen-qemu-dm-4.0 announced via advisory DSA 2543-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%202543-1

Multiple vulnerabilities have been discovered in xen-qemu-dm-4.0, the Xen Qemu Device Model virtual machine hardware emulator. The Common Vulnerabilities and Exposures project identifies the following problems: CVE-2012-3515: The device model for HVM domains does not properly handle VT100 escape sequences when emulating certain devices with a virtual console backend. An attacker within a guest with access to the vulnerable virtual console could overwrite memory of the device model and escalate privileges to that of the device model process. CVE-2012-4411: The qemu monitor was enabled by default, allowing administrators of a guest to access resources of the host, possibly escalate privileges or access resources belonging to another guest. For the stable distribution (squeeze), these problems have been fixed in version 4.0.1-2+squeeze2. The testing distribution (wheezy), and the unstable distribution (sid), no longer contain this package. We recommend that you upgrade your xen-qemu-dm-4.0 packages.