SANS is reporting a PDF exploit for iOS 7.1.x has been released. While this is patched in iOS 8, the adoption rate for this new iOS version has been slower than previous versions. Businesses have been in front, cautioning their users that upgrades should not occur until business apps have been tested. Additionally, the 5 Gb free space requirement has prevented impulse upgrades for some users.
To me, this is yet another example of Apple’s inattention to security. When Microsoft releases security updates they release them for every supported product at the same time.
Keep an eye out for a iOS upgrade if you’re running 7.