WebKit Proxy/Private Relay Leak Test Suite

Based on Mysk Blog, 2026-08-04: IP and DNS Leaks in WebKit Affecting Proxy Browsers and Apple iCloud Private Relay. Reference PoC: leaks.psylo.app

1. DNS prefetch leak

Click below to load a unique per-visit hostname via <link rel="dns-prefetch"> under d.leaktest.cgt.io, then check whether our authoritative DNS server saw the query.

2. WebAuthn Related Origin Requests leak

This test targets a different origin's rpId (rp.leaktest.cgt.io) from this page's own origin — that cross-origin mismatch is what should force the OS credential service to fetch rp.leaktest.cgt.io/.well-known/webauthn directly.

3. WebTransport leak

Opens a direct QUIC connection to wt.leaktest.cgt.io:4433.