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://openwall.com/lists/oss-security/2011/02/23/27
http://openwall.com/lists/oss-security/2011/02/24/10
https://bugzilla.redhat.com/show_bug.cgi?id=680094
http://secunia.com/advisories/50858
http://secunia.com/advisories/51024
http://secunia.com/advisories/51040
http://securitytracker.com/id?1025489
http://www.mandriva.com/security/advisories?name=MDVSA-2011:096
http://www.ubuntu.com/usn/USN-1596-1