The remote host is missing an update to policykit-1 announced via advisory DSA 2319-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%202319-1

Neel Mehta discovered that a race condition in Policykit, a framework for managing administrative policies and privileges, allowed local users to elevate privileges by executing a setuid program from pkexec. The oldstable distribution (lenny) does not contain the policykit-1 package. For the stable distribution (squeeze), this problem has been fixed in version 0.96-4+squeeze1. For the testing distribution (wheezy) and unstable distribution (sid), this problem has been fixed in version 0.101-4. We recommend that you upgrade your policykit-1 packages.