An issue was discovered in certain Apple products. iOS before 11.4 is affected. Safari before 11.1.1 is affected. iCloud before 7.5 on Windows is affected. iTunes before 12.7.5 on Windows is affected. tvOS before 11.4 is affected. The issue involves the "WebKit" component. It allows remote attackers to obtain sensitive credential information that is transmitted during a CSS mask-image fetch.