The iPhone 4S’s Siri is sassy and she’s everybody’s new favorite toy, but it turns out she’s leaving the door open for strangers to access of information on your phone even when it’s locked. Siri! How could you?

By default, users can activate Siri (iOS 5′s new digital assistant) even when the iPhone 4S is locked, which is incredibly convenient if it’s you that’s using your phone. But, as CNET is reporting, if someone else gets their hands on your phone, it could be very dangerous. Anyone who picks up your phone could get it to reveal your upcoming calendar appointments and know exactly where you are going to be and when. It can also be used to send emails or text messages.

There are some limitations. While it’s locked you can’t launch any apps, and you can’t send texts or emails to anyone who isn’t in your contacts, so that kind of thing could only be abused by someone who knows you, but I don’t find that particularly comforting.

The good news is that this can be disabled. In the Passcode Lock settings, all you have to do is switch Siri to “Off”. You’ll still be able to use Siri, just not when the phone is locked. Basically, you have to choose between convenience and security, but that’s your call. Still, it’s something we would definitely like to see them change in the next update. [CNET]