thttpd is a webserver designed to be simple, small, and fast.
thttpd is vulnerable to an underlying change made to the start-stop-daemon command in the current stable Gentoo baselayout package (version 1.12.6). In the new version, the start-stop-daemon command performs a "chdir /" command just before starting the thttpd process. In the Gentoo default configuration, this causes thttpd to start with the document root set to "/", the sytem root directory.
When thttpd starts with the document root set to the system root directory, all files on the system that are readable by the thttpd process can be remotely accessed by unauthenticated users.
Alter the THTTPD_OPTS variable in /etc/conf.d/thttpd to include the "-d" option to specify the document root. Alternatively, modify the THTTPD_OPTS variable in /etc/conf.d/thttpd to specify a thttpd.conf file using the "-C" option, and then configure the "dir=" directive in that thttpd.conf file.
All thttpd users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=www-servers/thttpd-2.25b-r5"