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fix(webhooks): block root-dotted internal hosts #52

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2 changes: 1 addition & 1 deletion lib/url-guard.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,7 @@ export function isInternalUrl(raw: string): boolean {
// Reject non-numeric ports; odd ports can hide alternate protocols.
if (u.port !== "" && !/^\d{1,5}$/.test(u.port)) return true;

const h = u.hostname.toLowerCase();
const h = u.hostname.toLowerCase().replace(/\.+$/, "");
if (h === "localhost" || h.endsWith(".localhost") || h === "metadata.google.internal") return true;
if (h === "0.0.0.0") return true;

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6 changes: 6 additions & 0 deletions tests/url-guard.test.mjs
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Expand Up @@ -19,6 +19,12 @@ test("SSRF guard blocks internal IPv4 special-use ranges", () => {
assert.equal(isInternalUrl("http://198.19.255.254/hook"), true);
});

test("SSRF guard blocks internal hostnames with DNS root dots", () => {
assert.equal(isInternalUrl("http://localhost./hook"), true);
assert.equal(isInternalUrl("http://app.localhost./hook"), true);
assert.equal(isInternalUrl("http://metadata.google.internal./hook"), true);
});

test("SSRF guard allows public IPv6 webhook targets", () => {
assert.equal(isInternalUrl("https://[2606:4700:4700::1111]/hook"), false);
assert.equal(isInternalUrl("https://[::ffff:8.8.8.8]/hook"), false);
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