Update, 7/9/2012 9:06AM PT: Illfonic reached out to us to correct some points in this story. It was previously believed that the security issues were with Crytek and CryEngine3 but Illfonic has informed us that the security issues are with a different 3rd party source, and not Crytek at all. The issue is simply getting the level editor to work properly in the game, and Illfonic has informed us that the term 'security measures' makes it sound a lot more threatening than it really is.
The original article can be found below.
Sad news today from the Illfonic camp. The upcoming Duel DLC for Nexuiz has been delayed indefinitely due to some security issues with CryEngine 3.
This isn't to say that Illfonic and THQ aren't working as hard as possible to get the Duel DLC released, but the fix needs to come from Crytek and Illfonic can't speak for them as to when it will be ready. The main problem seems to be a security issue that relates to the Nexuiz Level Editor, which would have allowed players to create custom maps and share them via Steam Workshop.
In the meantime, however, Illfonic wants to get as many of the bug fixes and game enhancements released as possible so they have begun prepping a new patch for the game which will bring dramatic performance updates as well as some other features.