The remote host is missing an update to qemu-kvm announced via advisory DSA 2282-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%202282-1

Two vulnerabilities have been discovered in KVM, a solution for full virtualization on x86 hardware: CVE-2011-2212 Nelson Elhage discovered a buffer overflow in the virtio subsystem, which could lead to denial of service or privilege escalation. CVE-2011-2527 Andrew Griffiths discovered that group privileges were insufficiently dropped when started with -runas option, resulting in privilege escalation. For the stable distribution (squeeze), this problem has been fixed in version 0.12.5+dfsg-5+squeeze6. For the unstable distribution (sid), this problem has been fixed in version 0.14.1+dfsg-3. We recommend that you upgrade your qemu-kvm packages.