The remote host is missing an update to xen-utils announced via advisory DSA 1395-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%201395-1

Steve Kemp from the Debian Security Audit project discovered that xen-utils, a collection of XEN administrative tools, used temporary files insecurely within the xenmon tool allowing local users to truncate arbitrary files. For the stable distribution (etch) this problem has been fixed in version 3.0.3-0-4. For the old stable distribution (sarge) this package was not present. For the unstable distribution (sid) this problem will be fixed soon. We recommend that you upgrade your xen-3.0 (3.0.3-0-4) package.