The rule-update feature in Cisco FireSIGHT Management Center (MC) 5.2 through 5.4.0.1 does not verify the X.509 certificate of the support.sourcefire.com SSL server, which allows man-in-the-middle attackers to spoof this server and provide an invalid package, and consequently execute arbitrary code, via a crafted certificate, aka Bug ID CSCuw06444.
The Cisco FireSIGHT Management Center appliance suffers from a certificate validation vulnerability. FirePWNER exploit included. Versions affected include 5.2.x, 5.3.x, and 5.4.x.