WIRED has an article of two security experts who managed to hack TrackingPoint system.
https://www.youtube.com/watch?v=BJPCYdjrNWs
Article: http://www.wired.com/2015/07/hackers-can-disable-sniper-rifleor-change-target/
Using WiFi, hackers gained root level control and vary the weight of bullet to change trajectory. In one instance, they were able to shoot target 2.5 feet to side. Even more shockingly, it could render the rifle useless by keeping the rifle unfirable.(Civilian version has this feature).
Furthermore, there are discussions of other theoretical hacks involving auxiliary devices such as smartphones, as well as subtle change to calculating paramters to make it miss just a little.
While enemy would not walk into WiFi range with an electronic device, it shows complex electronics can pose problems.
From: Wired
