A flaw in Google's Android Jellybean enables hackers to use fake apps to disable security mechanisms, leaving devices vulnerable to attacks, it is claimed.
German security firm Curesec claimed that the bug exists on the "com.android.settings.ChooseLockGeneric class".
The vulnerability allows any fake app to disable all device locks, including PIN, password, gesture and even facial recognition, activated by the smartphone user.
"This first piece of code allows the caller to actually control if the confirmation to change the lock mechanism is enabled or not," Curesec said.
"We can control the flow to reach the ['update preferences' function], and see that if we provide a password type, the flow continues to [the 'update and unlock' function]."
According to the security firm, if the password is of kind 'password_quality_unspecified,' the code gets executed and successfully unblocks the device.
The issue will not only enable hackers to bypass the lockscreen, said the security researchers, but also allows access to other confined areas of the device.
The issue was disclosed after Google's Android security team failed to effectively respond to the issue.
A Google spokesperson said the loophole is blocked in the latest version of Android, 'KitKat 4.4'.