This issue was addressed with improved handling of symlinks. This issue is fixed in iOS 18.1 and iPadOS 18.1, iOS 17.7.1 and iPadOS 17.7.1, visionOS 2.1, tvOS 18.1. Restoring a maliciously crafted backup file may lead to modification of protected system files.
https://support.apple.com/en-us/121569
https://support.apple.com/en-us/121567