An out-of-bounds read issue was addressed with improved input validation. This issue is fixed in visionOS 2.4, iOS 18.4 and iPadOS 18.4, tvOS 18.4, macOS Sequoia 15.4. Processing a maliciously crafted font may result in the disclosure of process memory.
https://support.apple.com/en-us/122378
https://support.apple.com/en-us/122377