Apple users with certain older generations of iPhones, iPads and an iPod are being urged to install a new security update.

In a Jan. 23 notice, Apple highlighted the impact of a recently discovered vulnerability picked up by Google's Threat Analysis Group.

The tech giant said that processing "maliciously crafted web content may lead to arbitrary code execution."

"Apple is aware of a report that this issue may have been actively exploited against versions of iOS released before iOS 15.1," it said.

Now, the iOS 12.5.7 update is available for affected devices.

Those devices include the iPhone 5s, iPhone 6, iPhone 6 Plus, iPad Air, iPad mini 2, iPad mini 3, and the sixth-generation iPod touch.

Two updates were announced in December: iOS 15.7.2 and iPadOS 15.7.2.

Apple previously said that those updates to address the issue were available for all iPhone 6 models, all iPhone 7 models, the first generation iPhone SE, all models of the iPad Pro, the iPad Air 2 and later, iPad 5th generation and later and the seventh generation iPod Touch.

To install the update on an iPhone, go to Settings, click General and then select Software Update.