Version 6.1.3 of iOS for the iPhone, iPad, and iPod Touch was released Tuesday, CNET reported.
Using the previous vulnerability, a person could execute a series of operations that including making a emergency call that would result in the phone's lock screen being bypassed, allowing them to make calls and listen to voice mails.
The update, which users can download to their phones for installation, "contains improvements and bug fixes," including the fix for "a bug that could allow someone to bypass the passcode and access the iPhone app," Apple said on its website.
In addition to the security fixes, the iOS 6.1.3 update also adds improvements to Apple Maps in Japan.
The lock screen flaw was discovered last month, but a subsequent 6.1.2 update to fix an email problem left the flaw in place until today's update.