The US Air Force, at least, requires no warranty of any software except firmware (e.g. for an airplane). Software crashes are not just commonplace, they are everyday, and "security" is almost entirely a joke. Other branches of the military do seem to have more cards in their decks, however.

This attitude makes me very nervous about airplanes landing on Air Force bases. Thankfully, NASA has quality testing and breathes down the Air Force's backs when dealing with the space program...