The problem is that the kernel devs (correctly imo) consider all bugfixes security fixes. So the distros need to decide for themselves which ones are important enough to warrant an update. Apparently this one had a quite unclear commit message, so it importance was missed.

Not ideal, but also: shit happens? It's always a balancing act choosing the lesser of multiple evils and most of the time it seems to work ok-ish, which is probably the best we can hope for ;-P