After recently fixing the "chaiOS" bug, Apple now has to contend with a nasty bug that will crash any Mac or iOS device that receives a single Indian-language character specific to the Telugu language. The bug doesn't affect every app - many third party apps are unaffected - but it's a major pain in the butt.
If the character, is received or pasted into iMessage, the app will crash, potentially taking the backend software that runs the iOS home screen with it. It's understood other communication apps including WhatsApp, Twitter, Facebook Messenger, Gmail and Outlook are also affected. However Telegram and Skype are OK. Apps on the Apple Watch and Mac are also hit.
On an iPhone, the issue is a pain as once you receive a message wth the character, you cannot get back into Messages until someone sends you a new message and you open it from the notification. Then, you can delete the affected message thread without opening the "infected" message. For email, you'll need to kill affected messages using a desktop mail or browser-based client on another device.
The bug has been addressed in the latest beta versions of macOS and iOS so it should be gone when the next software update is released. But until then, if you receive messages in the Telugu language, be careful