The game library rides the management REST API over HTTPS (TCP 47990) through
URLSession, authenticated by mTLS and pinned by SHA-256 fingerprint. The app
declared no App Transport Security policy at all, so it ran under default ATS --
which exempts only "local" destinations (.local, unqualified names, RFC1918 and
link-local literals) and applies the full policy everywhere else. The host
certificate is self-signed (and carries no SubjectAltName), so it cannot satisfy
that policy: the library loaded at 192.168.x and failed at the TLS layer on any
other address.
Field-reported against a Tailscale host. 100.64.0.0/10 is CGNAT, not RFC1918, so
the library failed there while streaming to the very same address worked -- the
QUIC stream plane is raw UDP and never enters the URL loading system. A WireGuard
peer or a public-IP host breaks identically.
Declares NSAllowsArbitraryLoads, which must stay the dict's only key: iOS 10+ and
macOS 10.12+ ignore it whenever a more granular ATS key sits alongside it. Trust
is unchanged -- LibraryTLSDelegate still pins the host by fingerprint and hands
every other origin (cover-art CDNs) to full system trust evaluation.
enricobuehler
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