BuzzFeed ad product intern and the founder of Hackers of NY Dani Grant was the one who discovered this particular glitch, where it would present you with someone else’s boarding pass whenever you alter the URL of your boarding pass. To make matters worse, if the person happens to be on a different airline, this particular glitch would still kick in, affecting them as well. In other words, with this glitch,you can check in on the other passenger, not to mention change their seat. Grant did alert Delta Airlines upon discovery of this particular flaw, but the response from the airline was far from satisfying.
Of course, there is a very easy way to fix this flaw, which would require airports to conduct extremely thorough identity checks, although there is no guarantee for all airports to do just that, especially when you take into consideration the holiday crowd that have their traveling plans at this time of the year. Hopefully something will be done by Delta Airlines before irate customers start to complain about an involuntary change of seats.