tldr; How far back does the TIFF exploit affect iOS and OS X legacy versions?
I've found conflicting information regarding how far back the recently reported image exploit can affect both iOS and OS X versions. The blog at Talos suggests that "all previous versions" are vulnerable; while This Reddit thread says that the proof of concept TIFF "didn't visibly crash Safari" on iOS 8.4 (emphasis added).
Obviously, the proof of concept TIFF may or may not match the exploit patched this week by Apple.
And Apple is not likely to offer up information on older OS versions it considers to be EOL.
So, the question is if there is a reliable place to provide info for both OS X and iOS legacy versions against this exploit?
Various stats generally show that around 15% of iOS devices are still running 8.4 or earlier; and, there is also an enclave of people who won't (or can't) update their computers beyond 10.6.8 or 10.9.5 for example.
A nicely referenced source regarding the vulnerability of these older OS versions would put many people's minds at ease.