Apple has said that all iPhones, iPads and Mac computers are affected by two major flaws in computer chips.
It emerged this week that tech companies have been racing to fix the Meltdown and Spectre bugs, that could allow hackers to steal data.
Billions of PCs, smartphones and tablets around the world are affected - Apple has now confirmed its products are too.
The firm has released some patches to mitigate the Meltdown flaw.
It said there was no evidence that either vulnerability had been exploited yet, but advised downloading software only from trusted sources to avoid "malicious" apps.
Mac users have often believed (WRONGLY) that their devices and operating systems are less vulnerable to security issues than, for example Android phones or computers running Microsoft systems.