The remote host is missing an update to lighttpd announced via advisory DSA 1521-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%201521-1

Julien Cayzac discovered that under certain circumstances lighttpd, a fast webserver with minimal memory footprint, might allow the reading of arbitrary files from the system. This problem could only occur with a non-standard configuration. For the stable distribution (etch), this problem has been fixed in version 1.4.13-4etch6. We recommend that you upgrade your lighttpd package.