Ruby is a dynamic, open source programming language with a focus on simplicity and productivity.
Zed Shaw, Jeremy Kemper, and Jamis Buck of the Mongrel project reported that the CGI library shipped with Ruby is vulnerable to a remote Denial of Service by an unauthenticated user.
The vulnerability can be exploited by sending the cgi.rb library an HTTP request with multipart MIME encoding that contains a malformed MIME boundary specifier beginning with "-" instead of "--". Successful exploitation of the vulnerability causes the library to go into an infinite loop waiting for additional nonexistent input.
There is no known workaround at this time.
All Ruby users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=dev-lang/ruby-1.8.5-r3"