fix: DNS rebinding protection checks AAAA (IPv6) records too#744
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Gonzih wants to merge 1 commit intogarrytan:mainfrom
Open
fix: DNS rebinding protection checks AAAA (IPv6) records too#744Gonzih wants to merge 1 commit intogarrytan:mainfrom
Gonzih wants to merge 1 commit intogarrytan:mainfrom
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resolvesToBlockedIp() was only calling resolve4() — an attacker could host a DNS entry with only AAAA records pointing to a blocked IPv6 metadata endpoint (fe80::, fd00::, etc.) and bypass the check entirely. Fix: - Check both A and AAAA records in parallel (Promise.all) - Block entire fe80::/10 link-local range, not just a single address - Add ::ffff:169.254.169.254 (IPv4-mapped IPv6) to the blocklist - Independent error handling per record family — ENODATA on one type doesn't suppress the other Closes garrytan#668
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The Gap
`resolvesToBlockedIp()` in `url-validation.ts` only called `resolve4()` (A records). A DNS rebinding attack using AAAA-only records pointing to IPv6 metadata endpoints (e.g. `fe80::1`, GCP's IPv6 metadata endpoint) bypassed the check completely.
Issue #668 documented this. Here's the fix.
Changes
The DNS calls were already async and run in parallel, so no performance regression.
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