The new iOS 9.0.2 update eliminates the Siri lockscreen vulnerability
At the time, we told you that going to Settings > Touch ID & Passcode > Allow access when locked, and setting the toggle switch to "no", would prevent this from taking place on your iPhone. Of course, by turning the toggle off, you would be removing some of the features available for Siri. But now that iOS 9.0.2 is being pushed out, once it is installed on your iPhone, you can turn the switch back to "on," allowing you to enjoy Siri just the way nature intended.
Just in case you haven't received iOS 9.0.2 yet, there is no need to panic or place a direct call to Tim Cook. The update was sent out in waves and it will eventually reach your iPhone. Just a quick reminder, when you are ready to download and install the 62.1MB update, you should use a Wi-Fi connection, and your battery should be at least 50% charged.
source: Apple via 9to5Mac