The is_cgi method in CGIHTTPServer.py in the CGIHTTPServer module in Python 2.5, 2.6, and 3.0 allows remote attackers to read script source code via an HTTP GET request that lacks a / (slash) character at the beginning of the URI.
http://www.ubuntu.com/usn/USN-1613-2
http://www.ubuntu.com/usn/USN-1613-1
http://www.ubuntu.com/usn/USN-1596-1
http://www.securityfocus.com/bid/46541
http://www.mandriva.com/security/advisories?name=MDVSA-2011:096
http://svn.python.org/view?view=revision&revision=71303
http://securitytracker.com/id?1025489
http://secunia.com/advisories/51040
http://secunia.com/advisories/51024