Apple has released an iOS 12 update users of older iPhone and iPad devices should download as soon as possible. The new version of the company’s 2018 operating system addresses a major vulnerability that Apple recently patched within iOS 15. According to a support document, the WebKit flaw could have allowed a website to run malicious code on your device. In its usual terse manner, Apple notes it is “aware of a report that this issue may have been actively exploited.”

For that reason, you should download the update as soon as possible if you’re still using an iOS 12 device. That’s a list that includes the iPhone 5s, iPhone 6, as well as iPad Air, iPad mini 2 and iPad mini 3. You can download iOS 12.5.6 by opening the Settings app, tapping on “General” and then selecting “Software Update.”