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.
MD5 checksums of the listed files are available in the original advisory.