Improper Access Control
WebKit in Apple iOS before 9.3 and Safari before 9.1 does not properly restrict redirects that specify a TCP port number, which allows remote attackers to bypass intended port restrictions via a crafted web site.
CWE-284 - Improper Access Control
Listed 5th in the 'OWASP Top Ten', improper (or broken) access control attacks are a fundamental type of vulnerability. This includes a broad range of design flaws that enable users to act outside of their intended permissions. They can use these privileges to gain access to restricted files and functionality such as accessing restricted information, falsifying records, destroying data, or executing commands.