Apple only publishes all iOS and macOS updates to the latest version of their operating systems. They release important updates to older operating systems (which is better than much of their competition!) but not all vulnerabilities are fixed for old versions.
You'll probably always be safe from remote code execution on supported versions of iOS/macOS, but exploits like these aren't always fixed. Unfortunately, you can't install an alternative browser engine on iOS/iPadOS, so I guess you should expect all websites to be able to read all of your cookies just in case.
You'll probably always be safe from remote code execution on supported versions of iOS/macOS, but exploits like these aren't always fixed. Unfortunately, you can't install an alternative browser engine on iOS/iPadOS, so I guess you should expect all websites to be able to read all of your cookies just in case.