An API issue existed in the handling of dictation requests. This issue was addressed with improved validation. This issue is fixed in iOS 12.2, macOS Mojave 10.14.4, tvOS 12.2, watchOS 5.2. A malicious application may be able to initiate a Dictation request without user authorization.
https://support.apple.com/HT209602
https://support.apple.com/HT209601