The remote host is missing an update to heimdal announced via advisory DSA 2372-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%202372-1

It was discovered that the Kerberos support for telnetd contains a pre-authentication buffer overflow, which may enable remote attackers who can connect to the Telnet to execute arbitrary code with root privileges. For the oldstable distribution (lenny), this problem has been fixed in version 1.2.dfsg.1-2.1+lenny1. For the stable distribution (squeeze), this problem has been fixed in version 1.4.0~git20100726.dfsg.1-2+squeeze1. For the testing distribution (wheezy) and the unstable distribution (sid), this problem will be fixed soon. We recommend that you upgrade your heimdal packages.