The remote host is missing an update to heimdal announced via advisory DSA 476-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%20476-1

According to a security advisory from the heimdal project: http://www.pdc.kth.se/heimdal/advisory/2004-04-01/ heimdal, a suite of software implementing the Kerberos protocol, has a cross-realm vulnerability allowing someone with control over a realm to impersonate anyone in the cross-realm trust path. For the current stable distribution (woody) this problem has been fixed in version 0.4e-7.woody.8.1. For the unstable distribution (sid), this problem has been fixed in version 0.6.1-1. We recommend that you update your heimdal package.