An issue was discovered in certain Apple products. iOS before 11.3 is affected. Safari before 11.1 is affected. iCloud before 7.4 on Windows is affected. iTunes before 12.7.4 on Windows is affected. tvOS before 11.3 is affected. watchOS before 4.3 is affected. The issue involves a JavaScriptCore function in the "WebKit" component. It allows attackers to trigger an assertion failure by leveraging improper array indexing.