CUPERTINO, Ca. – Apple issued an urgent security update on Thursday for OS X and Safari after finding the same vulnerabilities in its desktop operating system that were discovered last week in its mobile operating system and that allow attackers to remotely take control of a device.

The patch for OS X 10.11.6 “El Capitan” and 10.10.5 “Yosemite” comes a week after internet security experts discovered that a prominent Arab activist’s iPhone was being targeted by taking advantage of three previously unknown vulnerabilities in Apple’s mobile software. Apple responded by releasing an updated version of iOS: version 9.3.5.

The same vulnerabilities showed up in OS X because the desktop and mobile versions of the Safari browser share much of the same code base.

In its advisory, Apple warned that visiting a “maliciously crafted website” through its Safari browser could allow hackers to execute arbitrary code on a victim’s computer.