The remote host is missing an update to rp-pppoe, pppoe announced via advisory DSA 557-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%20557-1

Max Vozeler discovered a vulnerability in pppoe, the PPP over Ethernet driver from Roaring Penguin. When the program is running setuid root (which is not the case in a default Debian installation), an attacker could overwrite any file on the file system. For the stable distribution (woody) this problem has been fixed in version 3.3-1.2. For the unstable distribution (sid) this problem has been fixed in version 3.5-4. We recommend that you upgrade your pppoe package.