A permissions issue was addressed with additional restrictions. This issue is fixed in Safari 18.4, iOS 18.4 and iPadOS 18.4. Loading a malicious iframe may lead to a cross-site scripting attack.
https://support.apple.com/en-us/122379
https://support.apple.com/en-us/122371
https://lists.debian.org/debian-lts-announce/2025/06/msg00016.html