Apple's iOS 6.1.3 update, intended to fix a security vulnerability in a previous version of the software, has been causing the battery on users' handsets to drain quickly, as well as leaving a new lock-screen security flaw in place.
The update was released towards the beginning of last week in order to fix the initial lock-screen flaw, but users quickly began reporting on the Apple Technical Support forums and on Twitter that the battery life of their handsets had been draining much more quickly since installing the update.
"Last night I updated my iPhone 4S to iOS 6.1.3 and now it drains my battery in extremely fast manner. As I started signing in to write this question from my iPhone I already lost 13 percent of my battery. I never had a problem with a battery and I've been using iPhones since the first one," Timurjonchik wrote on Apple's forums on Thursday.
Others echoed the sentiment with similar complaints, including reports of dead batteries causing several people to miss their morning alarms.
The problems seem to be affecting devices regardless of mobile network or which model of the iPhone each person has.
"I'm not sure if the software varies at all between carriers but I'm on AT&T, not Verizon. My phone would hold 100 percent charge for over five hours on standby. Now within an hour it drains to 85 percent," a user by the name of TMercier added on the forum.
Other users have said that the problems can be mitigated by measures such as performing a hard reset and cycling battery charges. However, it seems that these do not help everyone.
"I have hard reset, cycled charges between 20 percent and full drain, removed apps in quick-switch, and there is zero improvement," TMercier added.
Other forum members suggested that switching off automatic updates for things such as email would extend the lifespan of the battery.
Apple had not responded to a request for comment at the time of writing.