I just found a security issue with iPhone.
You can access any contact information and even make calls even when the iPhone is locked.
Here's the steps to reproduce this:
TO SEE THE CONTACTS INFORMATION WHEN IPHONE IS LOCKED:
1. Long press on screen when the iPhone is Locked.
2. You will see that your Siri is activated.
3. Say any common name like "Mom Contact" or any name you feel a person may be having.
4. Siri will provide you the result of all possible matches for Contacts.
5. Now you can click on contact name to see the contact information.
TO CALL A NUMBER WHEN IPHONE IS LOCKED:
1. Long press on screen when the iPhone is Locked.
2. You will see that your Siri is activated.