The "Black Hole Maker" LHC has been switched on a couple days ago amidst high attention. The press was making fun of end of world fears triggered by the largest scientific experiment of mankind.
Now apparently some hackers have gotten pretty close in gaining control of one of the huge detectors of the LHC raising security concerns.
The LHC is a complex system and the scientists running it where actually a bit surprised that it worked from the get go. If a hacker could gain access and messes with the system it could have all kinds of effects.
It seems the network security of the CERN web servers is as old as the pages look.
More details on the Telegraph.