The remote host is missing an update to kfreebsd-8 announced via advisory DSA 2508-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%202508-1

Rafal Wojtczuk from Bromium discovered that FreeBSD wasn't handling correctly uncanonical return addresses on Intel amd64 CPUs, allowing privilege escalation to kernel for local users. For the stable distribution (squeeze), this problem has been fixed in version 8.1+dfsg-8+squeeze3. For the testing distribution (wheezy), this problem has been fixed in version 8.3-4. For the unstable distribution (sid), this problem has been fixed in version 8.3-4. We recommend that you upgrade your kfreebsd-8 packages.