Consumer electronics giant claims it is already working on a fix.
Apple iPhone users are being warned about a new security flaw affecting iOS 6.1, which allows hackers to bypass the smartphone’s lock-screen.
News of the flaw emerged earlier this week following the release of a YouTube video that walks users through the hack.
The video shows an iPhone running iOS 6.1 being unlocked using a series of steps involving the emergency call screen and the power button. The process takes under a minute and allows the phone's contacts, photos and call logs to be accessed.
At the time of writing, the video had been viewed more than 350,000 times.
In a statement, the consumer electronics giant said it was "aware of the issue" and working to deliver a fix in a future software updates.
This is not the first issue Apple has encountered problems with iOS 6.1 since its release on January 28.
It was reported that many iPhone 4S users were unable to make calls, send text messages or browse the internet after upgrading to iOS 6.1.
Mobile operator, Vodafone UK, even warned customers not to install iOS 6.1 until the bug was fixed, which resulted in a new version, iOS 6.1.1, being released for iPhone 4S users.
Meanwhile, some iOS 6.1 users have also noticed problems with the way their devices communicate with their company’s Microsoft Exchange Server, resulting in increased network activity and reduced battery life.