Apple has released security updates for a vulnerability that affects every iPhone, iPad, Mac and Apple Watch.

Citizen Lab, which discovered the vulnerability and was credited with the find, urges users to immediately update their devices.

Apple has said iOS 14.8 for iPhones and iPads, as well as new updates for Apple Watch and macOS, will fix at least one vulnerability that it said “may have been actively exploited.”

Citizen Lab first revealed details in August as part of an investigation into the use of a zero-day vulnerability that was used to silently hack into iPhones belonging to at least one Bahraini activist. They said the zero-day flaw — named as such since it gives companies zero days to roll out a fix — took advantage of a flaw in Apple’s iMessage, which was exploited to push the Pegasus spyware (developed by Israeli firm NSO Group) to the activist’s phone. Pegasus gives its government customers near-complete access to a target’s device, including their personal data, photos, messages and location.

The breach is significant because the flaws exploited the latest iPhone software at the time, both iOS 14.4 and later iOS 14.6, which Apple released in May. But also the exploit broke through new iPhone defenses that Apple had baked into iOS 14, which were supposed to prevent silent attacks by filtering potentially malicious code. The researchers said the exploit takes advantage of a weakness in how Apple devices render images on the display.

In a brief statement, Apple’s head of security engineering and architecture Ivan Krstić confirmed the fix:
“After identifying the vulnerability used by this exploit for iMessage, Apple rapidly developed and deployed a fix in iOS 14.8 to protect our users. We’d like to commend Citizen Lab for successfully completing the very difficult work of obtaining a sample of this exploit so we could develop this fix quickly. Attacks like the ones described are highly sophisticated, cost millions of dollars to develop, often have a short shelf life, and are used to target specific individuals. While that means they are not a threat to the overwhelming majority of our users, we continue to work tirelessly to defend all our customers, and we are constantly adding new protections for their devices and data.”