Passcode or no passcode, your iPhone can now be unlocked by anyone, enabling your roommate to easily grab all your most embarrassing photos, or giving a hacker access to your contacts. You can gauge which will do more damage to your peace of mind, but either way this is really scary stuff.
As BGR reports, a detrimental bug will let you enter an iPhone without a passcode by cleverly utilizing Siri, which you can of course call on while any iPhone is still locked. The first step to bypassing that lock screen is to ask Siri to "Search Twitter," and then asking her to search Twitter for the words "Gmail" or "Yahoo."
The goal here is to get Siri to bring up a list of tweets that contain email addresses. Once you find a valid email address, you need to 3D touch the address which will bring up a menu. With this menu, you can access both photos and contacts without ever needing a password or thumbprint.