This is the reason why I disable Siri from being used on the locked screen. It's barely inconvenient to have to unlock with fingerprint before being able to activate Siri, and the amount of information you can grab from a "locked" phone via Siri is scary.
Is there no way to disable sensitive requests from the lock screen? My Android phone has an option under voice settings to disable "Personal results" when the phone is locked.
With Siri, it's all or nothing. Either it is enabled on the lock screen, or completely inaccessible. It does have limits when enabled, where it will force you to unlock before inquiring deeper into the system. I can't remember exactly what kind of tasks I was able to accomplish with it enabled, but it was too much for me were it to land into a thief's hands. In any case, with the Touch ID it's barely an inconvenience to unlock before holding the home button to activate Siri. It's like 1.5 presses of the home button rather than a full 2. I'm not sure why they haven't put in the effort to allow you to hold down the home button once to activate Siri with a read of the fingerprint. They prioritized that action for Apple Pay. shrug
