lighttpd is a lightweight high-performance web server.
Julien Cayzax discovered that an insecure default setting exists in mod_userdir in lighttpd. When userdir.path is not set the default value used is $HOME. It should be noted that the "nobody" user's $HOME is "/" (CVE-2008-1270). An error also exists in the SSL connection code which can be triggered when a user prematurely terminates his connection (CVE-2008-1531).
A remote attacker could exploit the first vulnerability to read arbitrary files. The second vulnerability can be exploited by a remote attacker to cause a Denial of Service by terminating a victim's SSL connection.
As a workaround for CVE-2008-1270 you can set userdir.path to a sensible value, e.g. "public_html".
All lighttpd users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=www-servers/lighttpd-1.4.19-r2"