The remote host is missing an update to rdesktop announced via advisory DSA 1573-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%201573-1

Several remote vulnerabilities have been discovered in rdesktop, a Remote Desktop Protocol client. The Common Vulnerabilities and Exposures project identifies the following problems: CVE-2008-1801 Remote exploitation of an integer underflow vulnerability allows attackers to execute arbitrary code with the privileges of the logged-in user. CVE-2008-1802 Remote exploitation of a BSS overflow vulnerability allows attackers to execute arbitrary code with the privileges of the logged-in user. CVE-2008-1803 Remote exploitation of an integer signedness vulnerability allows attackers to execute arbitrary code with the privileges of the logged-in user. For the stable distribution (etch), these problems have been fixed in version 1.5.0-1etch2. For the unstable distribution (sid), these problems have been fixed in version 1.5.0-4+cvs20071006. We recommend that you upgrade your rdesktop package.