As the old saying goes, you either make the system simple enough there are obviously no vulnerabilities, or you make it complicated enough there are no obvious vulnerabilities.
(Of course "unknown" is relative. I'm curious about http://www.exploit-db.com/exploits/25444/ having "2010" in the copyright-like notice up top. I know the israeli secret service and russian kleptocracy and such have way better fuzzers than open source has bothered with until recently, the main protection for Ubuntu systems is we're less than 1% of the installed base so nobody _cares_. I'd worry more about android phones getting morris-wormed with something like this...)
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