Siri improved substantially on iOS 10, and over time is getting smarter, hopefully on iOS 11 Apple will give you another thread return and is above the other competitors currently. A Reddit user has discovered a bug in which Siri allows to disable mobile data with the iPhone locked, a major security problem if an iPhone is stolen.
The basis of this bug is that if we ask Siri to disable the mobile data, it will do so if the iPhone does not have any type of lock (password, PIN or fingerprint). Instead, if you have a lock, you will ask us to unlock the iPhone to perform the action. On the other hand, if we simply say “Mobile Data”, Siri shows us a toggle with which we can quickly deactivate the mobile data even while the device is locked
Analyzing the impact of this bug, we realize that it can be dangerous if we steal the terminal and remove the mobile data to avoid that we can trace the iPhone with “Where is my iPhone?“. But it is also true that there are many other means with which to remove the connection as activating the Airplane Mode from the Control Center.
On the other hand, if you worry about the security of your iPhone, deactivate Siri and Control Center on the screen lock. Thus, it will not be possible to activate the wizard with the screen locked and this bug will not be able to execute, an error that will last little longer until Apple will patches it.