As OP and many others have said, airline confirmation numbers are a pretty big personal security risk - an international itinerary always carries passport #, ad

As OP and many others have said, airline confirmation numbers are a pretty big personal security risk - an international itinerary always carries passport #, address, emergency info, et. A very bad practice I've seen over and over are people doing boarding-pass-selfies in airports, inadvertently exposing their confirmation numbers to entirety of their twitter/instagram/facebook feed. At best, you can move your buddy's girlfriend to be next to you on a flight instead, at worst, you can cancel their flight or move them to an earlier/later one. At very worst, you can use the plethora of PI data for ID theft.