There’s a new bug crashing iPhones when they receive a message or notification containing a certain string of characters. The offending combination of ASCII and unicode characters looks like this:
According to the thread on Reddit the text is causing iPhones to crash or reboot and a few have not recovered. There were also a few reports of the Apple Watch being affected by this as well.
I’m sure Apple will have a fix for this within the next week or two, but in the meantime if your Apple device starts rebooting or powering down for no reason – this could be the culprit. If you wish to follow the discussion on Reddit you can find the thread here: https://www.reddit.com/r/apple/comments/37enow/about_the_latest_iphone_security_vulnerability/