Directory traversal vulnerability in thttpd, when using virtual hosting, allows remote attackers to read arbitrary files via .. (dot dot) sequences in the Host: header.
https://www.debian.org/security/2003/dsa-396
http://news.php.net/article.php?group=php.cvs&article=15698
http://marc.info/?l=thttpd&m=103609565110472&w=2
http://distro.conectiva.com.br/atualizacoes/?id=a&anuncio=000777