Of course, the move to Lighttpd is not a small one, especially if our Apache configuration makes use of its many features. Systems tied into Apache as a module may make the move hard or even impossible without porting the module to a Lighttpd module or moving the functionality into CGI programs, if possible. We can ease the pain by moving in small steps. There are some obstacles on the way from Apache to Lighttpd. But a planned and careful approach will allow us to keep our server working while we change it.
cgi
Ruby: Another DoS Vulnerability in Ruby CGI Library
"Another vulnerability has been discovered in the CGI library (cgi.rb) that ships with Ruby which could be used by a malicious user to create a denial of service attack (DoS)."

