MacRumor reports that Apple has today released iOS 11.2.6, primarily to fix the bug that crashes various iOS apps, such as Messages, Safari, WhatsApp, Facebook Messenger, among others, when a particular Indian-language Telugu character is sent, received or even simply input.
Simply receiving the Telugu character in Messages will completely freeze up the whole Messages app on all of your Mac and iOS devices. It will continue to create problems with the Messages app, which will not work properly until the Telugu character is deleted from the conversation in which it was first sent.
Aside from this fix, the new update also solves an issue where some third-party apps are failing to connect to external accessories.
Apple has also fixed the Telugu character bug in iOS 11.3 and macOS 10.13.4, but this mini update was needed because iOS 11.3 and macOS 10.13.4 are still only in beta testing and are not due to launch until the spring.
Source: Apple Releases iOS 11.2.6 With Fix for Telugu Character Bug That Causes iOS Devices to Crash