Apple's latest 5.1 update of its mobile operating system iOS contains fixes for 81 security flaws.
The update, which was released last week, fixes a variety of vulnerabilities, including a fix to the lock screen of the iPad and iPhone.
Apple explained in its patch notes that it is possible to bypass the lock screen on unpatched devices, leaving any data on the device vulnerable should it be lost or stolen.
"A race condition issue existed in the handling of slide-to-dial gestures. This may allow a person with physical access to the device to bypass the Passcode Lock screen."
A race condition is a flaw in a process, where the result is dependent on the timing of certain other events; in this case, the action of swiping the lock icon on the device's screen.
There is also a fix for a cross-site scripting vulnerability, where malicious code on a website can be injected onto a user's machine.
Further fixes are included for iOS web browser Safari, voice control tool Siri and the iOS's virtual private network (VPN) feature.
The security improvements will be welcomed by IT departments, which are increasingly expected to support consumer devices such as iPhones and iPads.
A jailbreak was made available for version 5.1 of iOS within hours of its release. This enables non Apple-approved software to be installed on its devices.