The remote host is missing an update to x11-xserver-utils announced via advisory DSA 2213-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%202213-1

Sebastian Krahmer discovered that the xrdb utility of x11-xserver-utils, a X server resource database utility, is not properly filtering crafted hostnames. This allows a remote attacker to execute arbitrary code with root privileges given that either remote logins via xdmcp are allowed or the attacker is able to place a rogue DHCP server into the victims network. The oldstable distribution (lenny), this problem has been fixed in version 7.3+6. For the stable distribution (squeeze), this problem has been fixed in version 7.5+3. For the testing distribution (wheezy), this problem will be fixed soon. For the testing distribution (sid), this problem has been fixed in version 7.6+2. We recommend that you upgrade your x11-xserver-utils packages.