https://techcrunch.com/2018/02/19/update-for-ios-and-macs-negates-text-bomb-that-crashed-devices/

Last week we reported a major bug in Apple operating systems that would cause them to crash from mere exposure to either of two specific Unicode symbols. Today Apple fixes this major text-handling issue with iOS version 11.2.6 and macOS version 10.13.3, both now available for download.

The issue, discovered by Aloha Browser in the course of normal development, has to do with poor handling of certain non-English characters. We replicated the behavior, basically an immediate hard crash, in a variety of apps on both iOS and macOS. The vulnerability is listed on MITRE under CVE-2018-4124. If you were curious.