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fix(url-guard): block root-dotted internal hosts #85

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fix(url-guard): block root-dotted internal hosts #85

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5 changes: 5 additions & 0 deletions apps/web/lib/url-guard.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,11 @@ describe("validateExternalUrl (SSRF guard)", () => {
it("blocks localhost", () => {
expect(validateExternalUrl("http://localhost/x").ok).toBe(false);
});
it("blocks internal hostnames with DNS root dots", () => {
expect(validateExternalUrl("http://localhost./x").ok).toBe(false);
expect(validateExternalUrl("http://app.localhost./x").ok).toBe(false);
expect(validateExternalUrl("http://metadata.google.internal./x").ok).toBe(false);
});
it("blocks private 10.x", () => {
expect(validateExternalUrl("http://10.0.0.5/x").ok).toBe(false);
});
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3 changes: 2 additions & 1 deletion apps/web/lib/url-guard.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,7 @@ function isBlockedHost(host: string): boolean {
const ipv4 = ipv4FromMappedIPv6(host) ?? host;
return (
ipv4 === "localhost" ||
ipv4.endsWith(".localhost") ||
ipv4 === "0.0.0.0" ||
ipv4 === "::1" ||
ipv4 === "::" ||
Expand Down Expand Up @@ -42,7 +43,7 @@ export function validateExternalUrl(raw: string): { ok: true; url: URL } | { ok:
if (url.protocol !== "http:" && url.protocol !== "https:") {
return { ok: false, error: "Only http and https URLs are allowed." };
}
const host = url.hostname.toLowerCase().replace(/^\[(.*)\]$/, "$1");
const host = url.hostname.toLowerCase().replace(/^\[(.*)\]$/, "$1").replace(/\.+$/, "");
if (isBlockedHost(host)) {
return { ok: false, error: "That host is not allowed." };
}
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