Apple patched a high-severity iMessage bug found by Google Project Zero that can be exploited by an attacker who sends a specially-crafted message to a vulnerable iOS device. Those iPhones receiving the malicious message are rendered inoperable, or bricked. Apple patched the bug with the release of iOS 12.3 on May 13, 2019. As of June, according to iOS version tracking firm Statcounter, 47 percent of iOS devices worldwide are running a vulnerable version of the iOS 12.2 and below.
Source: https://threatpost.com/apple-patches-imessage-bug/146277/