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CCIP Read blocked RFC1918 and loopback on the resolved address, but ::ffff:127.0.0.1 is an IPv6 address so it skipped those networks. Unwrap ipv4_mapped before the blocklist so OffchainLookup URLs cannot reach loopback, link-local, or private IPv4 via mapped form.
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Summary
validate_ccip_url_host) rejects resolved addresses in RFC1918, loopback, link-local, and IPv6 ULA ranges so an OffchainLookup URL cannot send the client at private infrastructure.::ffff:127.0.0.1(and::ffff:10.0.0.1,::ffff:169.254.169.254) is an IPv6 address, so it is not a member of the IPv4 block list and the request proceeded.IPv6Address.ipv4_mappedbefore the blocklist. Public mapped addresses such as::ffff:8.8.8.8still pass.Attacker: a contract that returns OffchainLookup URLs. They already choose the URL. The guard is supposed to fail closed on private/reserved IPs after DNS. Mapped IPv6 skipped that guard.
Test plan
test_blocked_ipv4_mapped_ipv6for loopback, RFC1918, and link-local mapped formstest_public_ipv4_mapped_ipv6_passesfor::ffff:8.8.8.8_check_ip_blocked("::ffff:127.0.0.1")is falsenewsfragments/3875.bugfix.rst268493aCommit is SSH-signed.