IP and DNS Leaks in WebKit Affecting Proxy Browsers and iCloud Private Relay

Researchers discovered three WebKit features—DNS prefetching, WebAuthn Related Origin Requests, and WebTransport—that bypass proxy configurations on iOS and macOS, exposing users' real IP addresses and DNS servers. These leaks affect proxy-based browsers like Tor Browser and Psylo, as well as Apple's iCloud Private Relay, though the developers have released fixes that block or disable these features by default. The vulnerabilities do not affect traditional VPNs, which operate at the system level.