Malware
With the recent news about flame, stuxnet, and duqu, I find myself wondering if the NSA has put some backdoors in SE Linux. They wrote the code and its huge. It would be pretty easy to hide something there.
Its making me more paranoid.
But these kinds of attacks are so targeted I doubt they would do something like that. Plus, the code is available and everybody can see it. So once it is found, everybody would know who put it there.