feat: block CONNECT tunnels to private/reserved IP ranges - #23109
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March 17, 2026 12:27
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Documentation CheckUpdates Needed
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ssncferreira
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| return xerrors.Errorf("invalid resolved IP %q", resolvedIP) | ||
| } | ||
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| if s.isBlockedIP(ip, host, port) { |
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Nit: there's a bit of duplication with checkBlockedIP; these two funcs need to stay in-sync to ensure consistent behaviour.
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The only duplication here is the isBlockedIP check, the other logic is slightly different, so not sure if I can make create a helper function 😕
jdomeracki-coder
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Mar 18, 2026
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Looking good!
Left some additional hardening comments
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Approved ✅
One thing I'd like to verify experimentally is if this wouldn't break legitimate workloads attempting to communicate with the Cloud IMDS 🧪
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Description
Blocks
CONNECTtunnels to private and reserved IP ranges in aibridgeproxyd, preventing the proxy from being used to reach internal networks.The Coder access URL is always exempt (hostname+port match) so the proxy can reach its own deployment. It is possible to exempt additional ranges via
CODER_AIBRIDGE_PROXY_ALLOWED_PRIVATE_CIDRS.DNS rebinding is handled differently per path:
Changes
AllowedPrivateCIDRsoption with CLI flag and env varproxy.ConnectDialfor both upstream and direct pathsNotes: documentation will be handled in a follow-up PR.
Closes: https://github.com/coder/security/issues/124