Researchers from the Citizen Lab at the University of Toronto said the exploit had been in use since February and was used to deploy Pegasus, the spyware made by Israeli company NSO Group that was allegedly used to monitor journalists and human rights defenders in several countries.
Apple credited Citizen Lab researchers for finding the vulnerability.
“Attacks like the ones described are very sophisticated, cost millions of dollars to develop, often have a short lifespan, and are used to target specific individuals,” said Ivan Krstić, head of Apple Security Engineering and Architecture, in a statement.
Krstić said Apple quickly fixed the issue with a software patch and the vulnerability was “not a threat to the overwhelming majority of our users.”
Still, security experts have encouraged users to update their mobile devices to protect themselves.
In a statement, NSO Group did not respond to the allegations, stating only, “NSO Group will continue to provide intelligence and law enforcement agencies around the world with vital technologies to fight terrorism and crime.”
The company has previously said its software is only sold to approved customers for counter-terrorism and law enforcement purposes.
The researchers, however, say they have found several instances in which the spyware was deployed on dissidents or journalists. In 2019, Citizen Lab analysts alleged that Pegasus was used on the cellphone of the wife of a murdered Mexican journalist.