Officials at Mozilla have decided to disable support for Web Sockets in future versions of Firefox. The group said that demonstrations of serious attacks against WebSockets have spurred the move. Mozilla said that they plan to keep the WebSocket code in the Firefox 4 development tree, which is in beta right now, so that they have the ability to enable it again if the security concerns are cleared up in the future. The code will remain in the tree to facilitate development, but will only be activated when a developer sets a hidden preference in Firefox 4.
Source: https://threatpost.com/mozilla-disables-websockets-firefox-4-over-security-concerns-120810/74751/