It was reported that Fedora Atomic updates are trivially vulnerable to a MITM attack.
Upstream fix: https://git.fedorahosted.org/cgit/spin-kickstarts.git/commit/?id=1e408e111008f539c89212a9ca9bb955e2c4f823 Original report: https://bugzilla.redhat.com/showbug.cgi?id=1231287
fedora-cloud-atomic.ks in spin-kickstarts allows remote attackers to conduct man-in-the-middle attacks by leveraging use of HTTP to download Fedora Atomic updates.