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fix(security): reject userinfo in is_url_safe to prevent SSRF bypass (#97) #98

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Merged
HackingRepo merged 3 commits into from
Jun 2, 2026
+37 −72
Merged

fix(security): reject userinfo in is_url_safe to prevent SSRF bypass (#97) #98

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d6f23ec
fix(security): reject userinfo in is_url_safe to prevent SSRF bypass
andrewmkhoury May 29, 2026
83bee35
fix: address review comments — rebuild dist, fix is_redirect_safe
andrewmkhoury May 29, 2026
3958c4a
refactor: extract is_parsed_url_safe to eliminate duplicated checks
andrewmkhoury May 29, 2026
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52 changes: 17 additions & 35 deletions dist/helpers.js
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Original file line number Diff line number Diff line change
Expand Up @@ -383,16 +383,23 @@ function is_proto_safe(url) {
return true;
return false;
}
async function is_parsed_url_safe(parsed) {
if (!is_proto_safe(parsed.protocol))
return false;
if (parsed.username !== "" || parsed.password !== "")
return false;
// WHATWG URL includes brackets in .hostname for IPv6 (e.g. "[::1]"); strip them
const hostname = parsed.hostname.replace(/^\[|\]$/g, "");
if (await is_hostname_resolve_to_internal_ip(hostname))
return false;
return true;
}
async function is_redirect_safe(url) {
try {
let normalized = replace_backslash_with_slash_in_string(url);
normalized = remove_at_symbol_in_string(normalized);
let current = new URL(normalized);
let current = new URL(replace_backslash_with_slash_in_string(url));
const MAX_REDIRECTS = 5;
for (let i = 0; i < MAX_REDIRECTS; i++) {
if (!is_proto_safe(current.protocol))
return false;
if (await is_hostname_resolve_to_internal_ip(current.hostname))
if (!await is_parsed_url_safe(current))
return false;
const res = await got(current.toString(), {
method: "HEAD",
Expand All @@ -401,15 +408,9 @@ async function is_redirect_safe(url) {
timeout: { request: 3000 }
});
const loc = res.headers.location;
if (!loc) {
if (!loc)
return true;
}
try {
current = new URL(loc, current.toString());
}
catch {
return false;
}
current = new URL(loc, current.toString());
}
return false;
}
Expand All @@ -427,30 +428,11 @@ async function is_url_safe(url) {
let u = normalize_unicode(url);
u = replace_backslash_with_slash_in_string(u);
u = replace_two_slashes_url_to_normal_url(u);
u = remove_at_symbol_in_string(u);
const schema = normalize_schema(u);
if (!is_proto_safe(schema))
return false;
const parsed = new URL(u);
const hostname = parsed.hostname.replace(/^\[|\]$/g, "");
// IPv4 validation
if (/^\d{1,3}(\.\d{1,3}){3}$/.test(hostname)) {
try {
normalize_ipv4(hostname);
}
catch {
return false;
}
}
if (is_ipv6(hostname)) {
if (is_ip_internal(hostname))
return false;
}
if (await is_hostname_resolve_to_internal_ip(hostname))
if (!await is_parsed_url_safe(parsed))
return false;
if (process.env.DSSRF_CHECK_REDIRECTS === "1") {
const redirectSafe = await is_redirect_safe(u);
if (!redirectSafe)
if (!await is_redirect_safe(u))
return false;
}
return true;
Expand Down
1 change: 1 addition & 0 deletions dist/utils.js
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51 changes: 15 additions & 36 deletions src/helpers.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -448,17 +448,22 @@ export function is_proto_safe(url: string): boolean {



async function is_parsed_url_safe(parsed: URL): Promise<boolean> {
if (!is_proto_safe(parsed.protocol)) return false;
if (parsed.username !== "" || parsed.password !== "") return false;
// WHATWG URL includes brackets in .hostname for IPv6 (e.g. "[::1]"); strip them
const hostname = parsed.hostname.replace(/^\[|\]$/g, "");
if (await is_hostname_resolve_to_internal_ip(hostname)) return false;
return true;
}

export async function is_redirect_safe(url: string): Promise<boolean> {
try {
let normalized = replace_backslash_with_slash_in_string(url);
normalized = remove_at_symbol_in_string(normalized);

let current = new URL(normalized);
let current = new URL(replace_backslash_with_slash_in_string(url));

const MAX_REDIRECTS = 5;
for (let i = 0; i < MAX_REDIRECTS; i++) {
if (!is_proto_safe(current.protocol)) return false;
if (await is_hostname_resolve_to_internal_ip(current.hostname)) return false;
if (!await is_parsed_url_safe(current)) return false;

const res = await got(current.toString(), {
method: "HEAD",
Expand All @@ -468,15 +473,9 @@ export async function is_redirect_safe(url: string): Promise<boolean> {
});

const loc = res.headers.location;
if (!loc) {
return true;
}
if (!loc) return true;

try {
current = new URL(loc, current.toString());
} catch {
return false;
}
current = new URL(loc, current.toString());
}

return false;
Expand Down Expand Up @@ -504,35 +503,15 @@ export function normalize_unicode(input: string): string {
export async function is_url_safe(url: string): Promise<boolean> {
try {
let u = normalize_unicode(url);

u = replace_backslash_with_slash_in_string(u);
u = replace_two_slashes_url_to_normal_url(u);
u = remove_at_symbol_in_string(u);

const schema = normalize_schema(u);
if (!is_proto_safe(schema)) return false;

const parsed = new URL(u);
const hostname = parsed.hostname.replace(/^\[|\]$/g, "");

// IPv4 validation
if (/^\d{1,3}(\.\d{1,3}){3}$/.test(hostname)) {
try {
normalize_ipv4(hostname);
} catch {
return false;
}
}

if (is_ipv6(hostname)) {
if (is_ip_internal(hostname)) return false;
}

if (await is_hostname_resolve_to_internal_ip(hostname)) return false;
if (!await is_parsed_url_safe(parsed)) return false;

if (process.env.DSSRF_CHECK_REDIRECTS === "1") {
const redirectSafe = await is_redirect_safe(u);
if (!redirectSafe) return false;
if (!await is_redirect_safe(u)) return false;
}

return true;
Expand Down
5 changes: 4 additions & 1 deletion tsconfig.json
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Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,10 @@
"strict": true,
"declaration": true,
"outDir": "dist",
"esModuleInterop": true
"rootDir": "src",
"esModuleInterop": true,
"ignoreDeprecations": "6.0",
"types": ["node"]
},
"include": ["src"]
}
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