An issue was discovered in certain Apple products. iOS before 10.3 is affected. Safari before 10.1 is affected. tvOS before 10.2 is affected. The issue involves the "WebKit" component. It allows remote attackers to conduct Universal XSS (UXSS) attacks via crafted use of frames on a web site.
https://security.gentoo.org/glsa/201706-15
https://support.apple.com/HT207600
https://support.apple.com/HT207601