The remote host is missing an update to shadow announced via advisory DSA 1709-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%201709-1

Paul Szabo discovered that login, the system login tool, did not correctly handle symlinks while setting up tty permissions. If a local attacker were able to gain control of the system utmp file, they could cause login to change the ownership and permissions on arbitrary files, leading to a root privilege escalation. For the stable distribution (etch), this problem has been fixed in version 4.0.18.1-7+etch1. For the unstable distribution (sid), this problem has been fixed in version 4.1.1-6. We recommend that you upgrade your shadow package.