Ruby is an interpreted scripting language for quick and easy object-oriented programming. It comes bundled with HTTP ("WEBrick") and XMLRPC server objects.
Ruby uses blocking sockets for WEBrick and XMLRPC servers.
An attacker could send large amounts of data to an affected server to block the socket and thus deny other connections to the server.
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-1.8.4-r1"