A port redirection issue was addressed with additional port validation. This issue is fixed in macOS Big Sur 11.2, Security Update 2021-001 Catalina, Security Update 2021-001 Mojave, tvOS 14.4, watchOS 7.3, iOS 14.4 and iPadOS 14.4, Safari 14.0.3. A malicious website may be able to access restricted ports on arbitrary servers.
https://support.apple.com/en-us/HT212152
https://support.apple.com/en-us/HT212149
https://support.apple.com/en-us/HT212148
https://support.apple.com/en-us/HT212147
https://support.apple.com/en-us/HT212146