An issue was discovered in certain Apple products. iOS before 11.2.5 is affected. tvOS before 11.2.5 is affected. watchOS before 4.2.2 is affected. The issue involves the "Graphics Driver" component. It allows attackers to execute arbitrary code in a privileged context or cause a denial of service (memory corruption) via a crafted app.
https://support.apple.com/HT208464