A URL Unicode encoding issue was addressed with improved state management. This issue is fixed in iOS 13.6 and iPadOS 13.6, tvOS 13.4.8, watchOS 6.2.8, Safari 13.1.2, iTunes 12.10.8 for Windows, iCloud for Windows 11.3, iCloud for Windows 7.20. A malicious attacker may be able to conceal the destination of a URL.
A logic issue was addressed with improved restrictions. This issue is fixed in iOS 13.4 and iPadOS 13.4, macOS Catalina 10.15.4, tvOS 13.4, watchOS 6.2. Some websites may not have appeared in Safari Preferences.
A buffer overflow exists in the Brotli library versions prior to 1.0.8 where an attacker controlling the input length of a "one-shot" decompression request to a script can trigger a crash, which happens when copying over chunks of data larger than 2 GiB. It is recommended to update your Brotli library to 1.0.8 or later. If one cannot update, we recommend to use the "streaming" API as opposed to the "one-shot" API, and impose chunk size limits.