stealth: fingerprint consistency, scripted-request TLS, FormData

**Fingerprint consistency (stealth)** The stealth TLS, navigator, and WebGL surfaces previously disagreed. The wreq client reported Windows Chrome but navigator reported Linux, and WebGL returned Direct3D11 renderers for a Linux UA — a combination no real browser ever produces. Everything now presents one consistent Windows Chrome 145 identity: the HTTP User-Agent header, sec-ch-ua-platform, navigator.userAgent, navigator.platform, userAgentData, and WebGL renderer all agree. userAgentData brands are derived from the Chrome major version via Chromium's GREASE algorithm instead of a single hardcoded token.

**sec-ch-ua client hints on the default (non-stealth) path** The plain navigation client hardcoded `sec-ch-ua-platform: "Linux"` and Chrome 149 brands regardless of which profile was selected. Both headers are now derived from the actual User-Agent using the same GREASE algorithm, so non-stealth requests are also internally consistent.

**Route scripted fetch()/XHR through the stealth TLS client** In stealth mode, JS `fetch()` and `XMLHttpRequest` were still going through the plain reqwest/rustls stack, so subresource requests (sensors, WAF challenge verify calls) arrived with a non-browser TLS fingerprint. They now share the navigation's Chrome TLS fingerprint and sec-ch-ua client hints. The non-stealth path is unchanged.

**FormData serialization in fetch() — the booking.com fix** Passing a `FormData` as a `fetch()` or `XHR.send()` body sent the literal string `"[object Object]"` instead of a multipart payload. booking.com's AWS WAF challenge POSTs its proof-of-work solution to `/mp_verify` as FormData, so the verify always failed and no `aws-waf-token` was issued. `FormData` is now serialized to a proper `multipart/form-data` body with a generated boundary; `URLSearchParams` gets `application/x-www-form-urlencoded`. XHR routes through `fetch()` so it is covered too.

**navigator.permissions.query defaults** `permissions.query` returned `"granted"` for every permission. Real Chrome defaults camera, microphone, geolocation, and midi to `"prompt"`. Fixed.

**SHA-512/224 and SHA-512/256 in crypto.subtle.digest** Added FIPS 180-4 truncated SHA-512 variants to the Rust op and the JS allowlist. WAF challenge scripts that use these algorithms now get real output instead of a NotSupportedError.

**location updates synchronously on navigation, Blob-URL Worker race fixed**

crates/obscura-browser/Cargo.toml

@@ -5,7 +5,7 @@ edition.workspace = true
 
 [features]
 default = []
-stealth = ["obscura-net/stealth"]
+stealth = ["obscura-net/stealth", "obscura-js/stealth"]
 
 [dependencies]
 obscura-dom = { workspace = true }

crates/obscura-browser/src/page.rs

@@ -286,9 +286,11 @@ impl Page {
         if self.stealth_client.is_some() {
             rt.set_stealth(true);
             rt.set_user_agent(obscura_net::STEALTH_USER_AGENT);
-            // Match platform to the Linux UA so navigator.platform and
+            rt.set_platform(
-            // userAgentData.platform are consistent with navigator.userAgent.
+                obscura_net::STEALTH_NAVIGATOR_PLATFORM,
-            rt.set_platform("Linux x86_64", "Linux", "");
+                obscura_net::STEALTH_UA_PLATFORM,
+                obscura_net::STEALTH_UA_PLATFORM_VERSION,
+            );
         } else {
             if let Ok(ua) = self.http_client.user_agent.try_read() {
                 rt.set_user_agent(&ua);
@@ -317,6 +319,10 @@ impl Page {
         rt.set_cookie_jar(self.context.cookie_jar.clone());
         rt.set_http_client(self.http_client.clone());
         rt.set_blocked_urls(self.blocked_url_patterns.clone());
+        #[cfg(feature = "stealth")]
+        if let Some(ref stealth) = self.stealth_client {
+            rt.set_stealth_client(stealth.clone());
+        }
 
         if let Some(tx) = &self.intercept_tx {
             rt.set_intercept_tx(tx.clone());

crates/obscura-js/Cargo.toml

@@ -3,6 +3,13 @@ name = "obscura-js"
 version.workspace = true
 edition.workspace = true
 
+[features]
+default = []
+# Builds obscura-net with its stealth (wreq) HTTP client and lets scripted
+# fetch()/XHR be routed through it so JS-level requests carry the same Chrome
+# TLS fingerprint and client hints as stealth navigation.
+stealth = ["obscura-net/stealth"]
+
 [build-dependencies]
 deno_core = "0.350"
 

crates/obscura-js/js/bootstrap.js

@@ -154,7 +154,9 @@ function _fpNoise(x, y, channel) {
 var _fpCache = null;
 function _getFp() {
   if (_fpCache) return _fpCache;
-  const isMac = (globalThis.__obscura_ua_platform || 'Windows') === 'macOS';
+  const _uaPlat = globalThis.__obscura_ua_platform || 'Windows';
+  const isMac = _uaPlat === 'macOS';
+  const isLinux = _uaPlat === 'Linux';
   const gpuPool = isMac ? [
     'ANGLE (Apple, ANGLE Metal Renderer: Apple M1, Unspecified Version)',
     'ANGLE (Apple, ANGLE Metal Renderer: Apple M1 Pro, Unspecified Version)',
@@ -162,6 +164,14 @@ function _getFp() {
     'ANGLE (Apple, ANGLE Metal Renderer: Apple M2 Pro, Unspecified Version)',
     'ANGLE (Apple, ANGLE Metal Renderer: Apple M3, Unspecified Version)',
     'ANGLE (Intel Inc., ANGLE Metal Renderer: Intel(R) Iris(TM) Plus Graphics, Unspecified Version)',
+  ] : isLinux ? [
+    'ANGLE (Intel, Mesa Intel(R) UHD Graphics 630 (CFL GT2), OpenGL 4.6)',
+    'ANGLE (Intel, Mesa Intel(R) Iris(R) Xe Graphics (TGL GT2), OpenGL 4.6)',
+    'ANGLE (Intel, Mesa Intel(R) UHD Graphics 770 (RPL-S), OpenGL 4.6)',
+    'ANGLE (AMD, AMD Radeon RX 580 (polaris10, LLVM 15.0.7, DRM 3.54, LLVM 15.0.7), OpenGL 4.6)',
+    'ANGLE (AMD, AMD Radeon RX 6700 XT (navi22, LLVM 16.0.6, DRM 3.54, LLVM 16.0.6), OpenGL 4.6)',
+    'ANGLE (NVIDIA, NVIDIA GeForce RTX 3060 OpenGL 4.6)',
+    'ANGLE (NVIDIA, NVIDIA GeForce RTX 4070 OpenGL 4.6)',
   ] : [
     'ANGLE (NVIDIA, NVIDIA GeForce RTX 3060 Direct3D11 vs_5_0 ps_5_0, D3D11)',
     'ANGLE (NVIDIA, NVIDIA GeForce GTX 1660 SUPER Direct3D11 vs_5_0 ps_5_0, D3D11)',
@@ -180,6 +190,10 @@ function _getFp() {
     'Google Inc. (Apple)','Google Inc. (Apple)','Google Inc. (Apple)',
     'Google Inc. (Apple)','Google Inc. (Apple)',
     'Google Inc. (Intel Inc.)',
+  ] : isLinux ? [
+    'Google Inc. (Intel)','Google Inc. (Intel)','Google Inc. (Intel)',
+    'Google Inc. (AMD)','Google Inc. (AMD)',
+    'Google Inc. (NVIDIA)','Google Inc. (NVIDIA)',
   ] : [
     'Google Inc. (NVIDIA)','Google Inc. (NVIDIA)','Google Inc. (NVIDIA)',
     'Google Inc. (Intel)','Google Inc. (Intel)',
@@ -2577,7 +2591,7 @@ function __currentUrl() {
 }
 globalThis.location = {
   get href() { return __currentUrl(); },
-  set href(url) { globalThis.__virtualUrl = null; Deno.core.ops.op_navigate(_resolveUrl(url), 'GET', ''); },
+  set href(url) { var r = _resolveUrl(url); globalThis.__virtualUrl = r; Deno.core.ops.op_navigate(r, 'GET', ''); },
   get origin() { try { return new URL(this.href).origin; } catch { return ""; } },
   get protocol() { try { return new URL(this.href).protocol; } catch { return ""; } },
   get host() { try { return new URL(this.href).host; } catch { return ""; } },
@@ -2587,14 +2601,14 @@ globalThis.location = {
   get hash() { try { return new URL(this.href).hash; } catch { return ""; } },
   get port() { try { return new URL(this.href).port; } catch { return ""; } },
   toString() { return this.href; },
-  assign(url) { globalThis.__virtualUrl = null; Deno.core.ops.op_navigate(_resolveUrl(url), 'GET', ''); },
+  assign(url) { var r = _resolveUrl(url); globalThis.__virtualUrl = r; Deno.core.ops.op_navigate(r, 'GET', ''); },
-  reload() {},
+  reload() { var r = _resolveUrl(this.href); globalThis.__virtualUrl = r; Deno.core.ops.op_navigate(r, 'GET', ''); },
-  replace(url) { globalThis.__virtualUrl = null; Deno.core.ops.op_navigate(_resolveUrl(url), 'GET', ''); },
+  replace(url) { var r = _resolveUrl(url); globalThis.__virtualUrl = r; Deno.core.ops.op_navigate(r, 'GET', ''); },
 };
 const _locationObj = globalThis.location;
 Object.defineProperty(globalThis, 'location', {
   get() { return _locationObj; },
-  set(url) { Deno.core.ops.op_navigate(_resolveUrl(String(url)), 'GET', ''); },
+  set(url) { var r = _resolveUrl(String(url)); globalThis.__virtualUrl = r; Deno.core.ops.op_navigate(r, 'GET', ''); },
   configurable: false,
   enumerable: true,
 });
@@ -2752,8 +2766,35 @@ globalThis.NetworkInformation = NetworkInformation;
 
 globalThis.ContentIndex = class ContentIndex {};
 
+function _chromeMajor() {
+  var m = (globalThis.__obscura_ua || '').match(/Chrome\/(\d+)/);
+  return m ? (m[1] | 0) : 145;
+}
+// Chromium derives the sec-ch-ua GREASE brand, version, and brand order
+// deterministically from the Chrome major version
+// (components/embedder_support/user_agent_utils.cc). Replicating it keeps
+// sec-ch-ua and userAgentData exact for every profile version rather than
+// hardcoding one static token.
+var _GREASE_CHARS = [' ', '(', ':', '-', '.', '/', ')', ';', '=', '?', '_'];
+var _GREASE_VER = ['8', '99', '24'];
+var _BRAND_PERMS = [[0,1,2],[0,2,1],[1,0,2],[1,2,0],[2,0,1],[2,1,0]];
+function _uaBrands() {
+  var seed = _chromeMajor();
+  var grease = {
+    brand: 'Not' + _GREASE_CHARS[seed % 11] + 'A' + _GREASE_CHARS[(seed + 1) % 11] + 'Brand',
+    version: _GREASE_VER[seed % 3],
+  };
+  var ordered = [
+    grease,
+    {brand: 'Chromium', version: String(seed)},
+    {brand: 'Google Chrome', version: String(seed)},
+  ];
+  var p = _BRAND_PERMS[seed % 6];
+  return [ordered[p[0]], ordered[p[1]], ordered[p[2]]];
+}
+
 globalThis.navigator = {
-  get userAgent() { return globalThis.__obscura_ua || "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/145.0.0.0 Safari/537.36"; },
+  get userAgent() { return globalThis.__obscura_ua || "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/145.0.0.0 Safari/537.36"; },
   get appVersion() { return this.userAgent.replace('Mozilla/', ''); },
   language: "en-US", languages: ["en-US","en"], get platform() { return globalThis.__obscura_platform || "Win32"; },
   onLine: true, cookieEnabled: true, hardwareConcurrency: 8,
@@ -2779,24 +2820,22 @@ globalThis.navigator = {
     ]);
   },
   userAgentData: {
-    brands: [
-      {brand: "Google Chrome", version: "145"},
-      {brand: "Chromium", version: "145"},
-      {brand: "Not;A=Brand", version: "24"},
-    ],
     mobile: false,
+    get brands() { return _uaBrands(); },
     get platform() { return globalThis.__obscura_ua_platform || "Windows"; },
     getHighEntropyValues(hints) {
+      var brands = _uaBrands();
       return Promise.resolve({
         architecture: "x86",
         bitness: "64",
-        brands: [{brand:"Google Chrome",version:"145"},{brand:"Chromium",version:"145"},{brand:"Not;A=Brand",version:"24"}],
+        brands: brands,
-        fullVersionList: [{brand:"Google Chrome",version:"145.0.0.0"},{brand:"Chromium",version:"145.0.0.0"},{brand:"Not;A=Brand",version:"24.0.0.0"}],
+        fullVersionList: brands.map(function(b) { return {brand: b.brand, version: b.version + ".0.0.0"}; }),
         mobile: false,
         model: "",
         platform: globalThis.__obscura_ua_platform || "Windows",
         platformVersion: globalThis.__obscura_ua_platform_version || "15.0.0",
-        uaFullVersion: "145.0.0.0",
+        uaFullVersion: _chromeMajor() + ".0.0.0",
+        wow64: false,
       });
     },
     toJSON() { return {brands:this.brands,mobile:this.mobile,platform:this.platform}; },
@@ -2817,8 +2856,12 @@ globalThis.navigator = {
   },
   clipboard: { writeText(){return Promise.resolve();}, readText(){return Promise.resolve("");} },
   permissions: { query(params){
-    if (params?.name === 'notifications') return Promise.resolve({state:"prompt",onchange:null});
+    var n = params && params.name;
-    return Promise.resolve({state:"granted"});
+    // Chrome defaults privacy-sensitive permissions to "prompt", not "granted";
+    // returning "granted" for camera/microphone is a bot tell.
+    if (n === 'notifications') return Promise.resolve({state: (globalThis.Notification && Notification.permission === 'granted') ? 'granted' : 'prompt', onchange: null});
+    if (n === 'geolocation' || n === 'camera' || n === 'microphone' || n === 'midi') return Promise.resolve({state: 'prompt', onchange: null});
+    return Promise.resolve({state: 'granted', onchange: null});
   } },
   getBattery() { return Promise.resolve({ charging: _fp('batteryCharging'), chargingTime: _fp('batteryCharging') ? 0 : Infinity, dischargingTime: _fp('batteryCharging') ? Infinity : Math.floor(3600 + _fpRand(250) * 7200), level: _fp('batteryLevel'), addEventListener(){} }); },
   getGamepads() { return []; },
@@ -3003,6 +3046,51 @@ function _installWasmStreamingFallback() {
 }
 _installWasmStreamingFallback();
 
+// Serialize a FormData into a multipart/form-data body the way a browser does
+// when it is passed as fetch()/XHR body. The previous shim did String(body),
+// so a FormData became the literal "[object Object]" and the multipart payload
+// (with its boundary) was lost; servers replied "Invalid boundary for
+// multipart/form-data" (e.g. the AWS WAF challenge /mp_verify POST).
+function _formDataToMultipart(fd) {
+  const chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
+  let bnd = '----WebKitFormBoundary';
+  for (let i = 0; i < 16; i++) bnd += chars[Math.floor(Math.random() * chars.length)];
+  let out = '';
+  const entries = fd._d || [];
+  for (let i = 0; i < entries.length; i++) {
+    const k = entries[i][0], v = entries[i][1];
+    out += '--' + bnd + '\r\n';
+    if (v != null && typeof v === 'object' && v._bytes != null) {
+      out += 'Content-Disposition: form-data; name="' + k + '"; filename="' + (v.name || 'blob') + '"\r\n';
+      out += 'Content-Type: ' + (v.type || 'application/octet-stream') + '\r\n\r\n';
+      try { out += new TextDecoder().decode(v._bytes); } catch (e) {}
+      out += '\r\n';
+    } else {
+      out += 'Content-Disposition: form-data; name="' + k + '"\r\n\r\n' + String(v) + '\r\n';
+    }
+  }
+  out += '--' + bnd + '--\r\n';
+  return { boundary: bnd, body: out };
+}
+
+// Coerce a fetch()/XHR body into the string op_fetch_url expects, attaching a
+// Content-Type header for body types that need one (FormData, URLSearchParams).
+function _serializeBody(initBody, headers) {
+  if (initBody == null || initBody === '') return '';
+  if (initBody instanceof FormData) {
+    const mp = _formDataToMultipart(initBody);
+    headers['Content-Type'] = 'multipart/form-data; boundary=' + mp.boundary;
+    return mp.body;
+  }
+  if (initBody instanceof URLSearchParams) {
+    if (!Object.keys(headers).some(k => k.toLowerCase() === 'content-type')) {
+      headers['Content-Type'] = 'application/x-www-form-urlencoded;charset=UTF-8';
+    }
+    return initBody.toString();
+  }
+  return typeof initBody === 'string' ? initBody : String(initBody);
+}
+
 globalThis.fetch = async (input, init = {}) => {
   let url = typeof input === "string"
     ? input
@@ -3016,8 +3104,9 @@ globalThis.fetch = async (input, init = {}) => {
     } catch(e) { /* keep as-is if URL resolution fails */ }
   }
   const method = init.method || (input instanceof Request ? input.method : "GET");
-  const hdrs = JSON.stringify(init.headers instanceof Headers ? Object.fromEntries(init.headers.entries()) : init.headers || {});
+  let _h = init.headers instanceof Headers ? Object.fromEntries(init.headers.entries()) : (init.headers || {});
-  const body = init.body ? String(init.body) : "";
+  const body = _serializeBody(init.body, _h);
+  const hdrs = JSON.stringify(_h);
   const fetchMode = init.mode || (input instanceof Request ? input.mode : "cors");
   const pageOrigin = (function() { try { const u = new URL(_domParse("document_url") || "about:blank"); return u.origin; } catch(e) { return ""; } })();
   const raw = await Deno.core.ops.op_fetch_url(url, method, hdrs, body, pageOrigin, fetchMode);
@@ -6328,11 +6417,25 @@ globalThis.Worker = class Worker {
 };
 
 globalThis.__blobStore = globalThis.__blobStore || {};
-const _origCreateObjectURL = URL.createObjectURL;
 URL.createObjectURL = function(blob) {
-  if (blob && typeof blob.text === 'function') {
+  if (blob) {
     const id = 'blob:obscura/' + Math.random().toString(36).substring(2);
+    // Store synchronously so a Worker built from the blob URL in the same
+    // tick sees its source. Blob-URL Worker construction is synchronous in
+    // real browsers; the previous async blob.text().then() store raced the
+    // Worker constructor, so new Worker(blobURL) fell through to fetch() and
+    // failed (net::ERR_FAILED), which broke AWS WAF's proof-of-work worker.
+    // The obscura Blob materializes _bytes in its constructor; fall back to
+    // the async text() store only for foreign Blob shims without _bytes.
+    if (blob._bytes) {
+      let text = '';
+      try { text = new TextDecoder().decode(blob._bytes); } catch (e) {}
+      globalThis.__blobStore[id] = text;
+    } else if (typeof blob.text === 'function') {
       blob.text().then(text => { globalThis.__blobStore[id] = text; });
+    } else {
+      globalThis.__blobStore[id] = '';
+    }
     return id;
   }
   return 'blob:obscura/fallback';
@@ -6421,7 +6524,8 @@ if (!globalThis.crypto.subtle) {
   globalThis.crypto.subtle = {
     async digest(algorithm, data) {
       const name = (typeof algorithm === 'string' ? algorithm : algorithm?.name || '').toUpperCase().replace('_', '-');
-      if (name !== 'SHA-1' && name !== 'SHA-256' && name !== 'SHA-384' && name !== 'SHA-512') {
+      if (name !== 'SHA-1' && name !== 'SHA-256' && name !== 'SHA-384' && name !== 'SHA-512' &&
+          name !== 'SHA-512/224' && name !== 'SHA-512/256') {
         throw new DOMException('Unrecognized algorithm name', 'NotSupportedError');
       }
       let bytes;
@@ -6840,6 +6944,10 @@ if (typeof ShadowRoot !== 'undefined' && !ShadowRoot.prototype.elementFromPoint)
 globalThis.__obscura_init = function() {
   _fpSeed = Date.now() ^ (Math.random() * 0xFFFFFFFF >>> 0);
   _fpCache = null;
+  // A real navigation just completed (this runs after set_url), so drop any
+  // URL a location setter previewed synchronously and let document_url drive
+  // location.href again, including any redirect target.
+  globalThis.__virtualUrl = null;
   _installWasmStreamingFallback();
 
   globalThis.document = new Document(+_dom("document_node_id"));
@@ -6868,29 +6976,9 @@ globalThis.__obscura_init = function() {
   };
   globalThis.Notification.permission = "default";
 
-  if (globalThis.__obscura_stealth) {
+  // userAgentData brands and getHighEntropyValues now derive the Chrome
-    var _stealthBrands = [
+  // version from navigator.userAgent and read the platform from the page
-      {brand: "Not:A-Brand", version: "99"},
+  // globals, so every stealth surface agrees without a per-mode override.
-      {brand: "Google Chrome", version: "145"},
-      {brand: "Chromium", version: "145"},
-    ];
-    globalThis.navigator.userAgentData.brands = _stealthBrands;
-    globalThis.navigator.userAgentData.getHighEntropyValues = function(hints) {
-      return Promise.resolve({
-        architecture: "x86", bitness: "64",
-        brands: _stealthBrands,
-        fullVersionList: [
-          {brand:"Not:A-Brand",version:"99.0.0.0"},
-          {brand:"Google Chrome",version:"145.0.0.0"},
-          {brand:"Chromium",version:"145.0.0.0"},
-        ],
-        mobile: false, model: "",
-        platform: "Windows",
-        platformVersion: "10.0.0",
-        uaFullVersion: "145.0.0.0",
-      });
-    };
-  }
 
   // Hide internals (_*, obscura, Obscura). The set of keys is static at
   // snapshot-build time, so we precompute it ONCE below (after this

crates/obscura-js/src/ops.rs

@@ -9,6 +9,8 @@ use deno_core::Extension;
 use base64::{engine::general_purpose::STANDARD as BASE64, Engine as _};
 use obscura_dom::{DomTree, NodeData, NodeId};
 use obscura_net::{CookieJar, ObscuraHttpClient};
+#[cfg(feature = "stealth")]
+use obscura_net::StealthHttpClient;
 use tokio::sync::Mutex;
 
 pub type InterceptCallback = Arc<Mutex<Option<Box<dyn Fn(String, String, String) -> Option<(u16, String, String)> + Send + Sync>>>>;
@@ -55,6 +57,11 @@ pub struct ObscuraState {
     pub blocked_urls: Vec<String>,
     pub cookie_jar: Option<Arc<CookieJar>>,
     pub http_client: Option<Arc<ObscuraHttpClient>>,
+    /// When set (stealth mode), scripted fetch()/XHR is routed through the wreq
+    /// client so the request carries the Chrome TLS fingerprint and client
+    /// hints instead of the rustls ClientHello op_fetch_url would otherwise send.
+    #[cfg(feature = "stealth")]
+    pub stealth_client: Option<Arc<StealthHttpClient>>,
     pub pending_navigation: Option<(String, String, String)>,
     pub intercept_tx: Option<tokio::sync::mpsc::UnboundedSender<InterceptedRequest>>,
     pub intercept_counter: u64,
@@ -82,6 +89,8 @@ impl ObscuraState {
             blocked_urls: Vec::new(),
             cookie_jar: None,
             http_client: None,
+            #[cfg(feature = "stealth")]
+            stealth_client: None,
             pending_navigation: None,
             intercept_tx: None,
             intercept_counter: 0,
@@ -707,6 +716,34 @@ async fn op_fetch_url(
     let custom_headers: std::collections::HashMap<String, String> =
         serde_json::from_str(&headers_json).unwrap_or_default();
 
+    // Stealth mode: route the scripted request through the wreq client so its
+    // TLS fingerprint and Chrome client hints match the main navigation. The
+    // rustls ClientHello plus missing client hints that op_fetch_url's reqwest
+    // path sends otherwise read as a non-browser script to bot managers (the
+    // AWS WAF challenge verify call, Akamai sensors, etc.).
+    #[cfg(feature = "stealth")]
+    {
+        let stealth = {
+            let st = state.borrow();
+            let gs = st.borrow::<SharedState>().clone();
+            let client = gs.borrow().stealth_client.clone();
+            client
+        };
+        if let Some(stealth) = stealth {
+            return stealth_fetch_all(
+                stealth,
+                url.clone(),
+                req_method.as_str().to_string(),
+                custom_headers.clone(),
+                body.clone(),
+                page_origin.clone(),
+                is_cross_origin,
+                mode.clone(),
+            )
+            .await;
+        }
+    }
+
     let needs_preflight = is_cross_origin
         && mode == "cors"
         && (req_method != reqwest::Method::GET
@@ -946,6 +983,120 @@ async fn op_fetch_url(
     .to_string())
 }
 
+/// Stealth-mode scripted fetch()/XHR: mirrors op_fetch_url's redirect, SSRF,
+/// and CORS semantics but sends every hop through the wreq stealth client so
+/// the request carries the Chrome TLS fingerprint and client hints. Cookie
+/// handling lives inside StealthHttpClient::send_single, which shares the
+/// context jar. Response bodies are not mirrored into the CDP
+/// Network.getResponseBody buffer here; that is a follow-up for stealth fetches.
+#[cfg(feature = "stealth")]
+async fn stealth_fetch_all(
+    stealth: Arc<StealthHttpClient>,
+    url: String,
+    method: String,
+    custom_headers: HashMap<String, String>,
+    body: String,
+    page_origin: String,
+    is_cross_origin: bool,
+    mode: String,
+) -> Result<String, deno_error::JsErrorBox> {
+    let mut current_url = url.clone();
+    let mut current_method = method;
+    let mut current_body = body;
+    let mut redirects_followed: usize = 0;
+
+    let (status, resp_headers, resp_bytes): (u16, HashMap<String, String>, Vec<u8>) = loop {
+        let parsed_current = match url::Url::parse(&current_url) {
+            Ok(u) => u,
+            Err(_) => {
+                return Ok(serde_json::json!({
+                    "status": 0, "body": "", "url": current_url, "headers": {},
+                })
+                .to_string());
+            }
+        };
+
+        let mut req_headers: HashMap<String, String> = HashMap::new();
+        if is_cross_origin {
+            req_headers.insert("origin".to_string(), page_origin.clone());
+        }
+        for (k, v) in &custom_headers {
+            req_headers.insert(k.to_lowercase(), v.clone());
+        }
+
+        let r = stealth
+            .send_single(&current_method, &parsed_current, &req_headers, &current_body)
+            .await
+            .map_err(|e| deno_error::JsErrorBox::generic(e.to_string()))?;
+
+        if !(300..400).contains(&r.status) {
+            break (r.status, r.headers, r.body);
+        }
+        let Some(location) = r.headers.get("location").cloned() else {
+            break (r.status, r.headers, r.body);
+        };
+        let next_url = match parsed_current.join(&location) {
+            Ok(u) => u,
+            Err(_) => break (r.status, r.headers, r.body),
+        };
+        // Re-validate every redirect target against the SSRF policy, matching
+        // op_fetch_url (GHSA-8v6v-g4rh-jmcm).
+        if let Err(reason) = validate_fetch_url(&next_url) {
+            return Ok(serde_json::json!({
+                "status": 0, "body": "", "url": next_url.to_string(), "headers": {},
+                "blocked": true,
+                "error": format!("Redirect to forbidden URL blocked: {}", reason),
+            })
+            .to_string());
+        }
+        redirects_followed += 1;
+        if redirects_followed > FETCH_REDIRECT_LIMIT {
+            return Ok(serde_json::json!({
+                "status": 0, "body": "", "url": next_url.to_string(), "headers": {},
+                "blocked": true,
+                "error": format!("Too many redirects (>{})", FETCH_REDIRECT_LIMIT),
+            })
+            .to_string());
+        }
+        // Browser semantics: 301/302/303 downgrade to GET with no body.
+        if r.status == 301 || r.status == 302 || r.status == 303 {
+            current_method = "GET".to_string();
+            current_body.clear();
+        }
+        current_url = next_url.to_string();
+    };
+
+    if is_cross_origin && mode == "cors" {
+        let allowed = resp_headers
+            .get("access-control-allow-origin")
+            .map(|s| s.as_str())
+            .unwrap_or("");
+        if allowed != "*" && allowed != page_origin {
+            return Ok(serde_json::json!({
+                "status": 0, "body": "", "url": url, "headers": {},
+                "corsBlocked": true,
+                "corsError": format!(
+                    "CORS error: Origin '{}' not in Access-Control-Allow-Origin '{}'",
+                    page_origin, allowed
+                ),
+            })
+            .to_string());
+        }
+    }
+
+    let resp_body = String::from_utf8_lossy(&resp_bytes).to_string();
+    let resp_body_base64 = BASE64.encode(&resp_bytes);
+
+    Ok(serde_json::json!({
+        "status": status,
+        "body": resp_body,
+        "bodyBase64": resp_body_base64,
+        "url": url,
+        "headers": resp_headers,
+    })
+    .to_string())
+}
+
 fn glob_match(pattern: &str, url: &str) -> bool {
     if pattern == "*" {
         return true;
@@ -1107,8 +1258,9 @@ fn op_binding_called(state: &OpState, #[string] name: &str, #[string] payload: &
 }
 
 /// Real WebCrypto `crypto.subtle.digest`. `algorithm` is the SubtleCrypto
-/// algorithm name (`SHA-1` / `SHA-256` / `SHA-384` / `SHA-512`). The JS shim
+/// algorithm name (`SHA-1` / `SHA-256` / `SHA-384` / `SHA-512`, plus the
-/// validates the name before calling this op; any other value is unreachable.
+/// FIPS 180-4 truncated variants `SHA-512/224` and `SHA-512/256`). The JS
+/// shim validates the name; any other value is unreachable.
 /// Returns the raw digest bytes so the JS shim can hand them back as an ArrayBuffer.
 #[op2]
 #[buffer]
@@ -1120,6 +1272,8 @@ fn op_subtle_digest(#[string] algorithm: &str, #[buffer] data: &[u8]) -> Vec<u8>
         "SHA-256" => sha2::Sha256::digest(data).to_vec(),
         "SHA-384" => sha2::Sha384::digest(data).to_vec(),
         "SHA-512" => sha2::Sha512::digest(data).to_vec(),
+        "SHA-512/224" => sha2::Sha512_224::digest(data).to_vec(),
+        "SHA-512/256" => sha2::Sha512_256::digest(data).to_vec(),
         _ => vec![],
     }
 }

crates/obscura-js/src/runtime.rs

@@ -153,6 +153,13 @@ impl ObscuraJsRuntime {
         self.state.borrow_mut().http_client = Some(client);
     }
 
+    /// Install the stealth (wreq) HTTP client so scripted fetch()/XHR is routed
+    /// through it in stealth mode (see op_fetch_url / stealth_fetch_all).
+    #[cfg(feature = "stealth")]
+    pub fn set_stealth_client(&self, client: std::sync::Arc<obscura_net::StealthHttpClient>) {
+        self.state.borrow_mut().stealth_client = Some(client);
+    }
+
     pub fn set_dom(&self, dom: DomTree) {
         self.state.borrow_mut().dom = Some(dom);
     }

crates/obscura-net/src/client.rs

@@ -273,6 +273,46 @@ pub struct ObscuraHttpClient {
     pub allow_private_network: bool,
 }
 
+/// Derive the sec-ch-ua and sec-ch-ua-platform client-hint header values from a
+/// User-Agent string, using Chromium's per-major-version GREASE algorithm so
+/// the non-stealth HTTP path agrees with navigator.userAgentData instead of
+/// shipping a fixed Linux/Chrome-145 hint that contradicts a Windows profile.
+fn chrome_client_hints(ua: &str) -> (String, String) {
+    let major: usize = ua
+        .split("Chrome/")
+        .nth(1)
+        .and_then(|s| s.split('.').next())
+        .and_then(|s| s.parse::<usize>().ok())
+        .unwrap_or(145);
+    const GREASE_CHARS: [char; 11] = [' ', '(', ':', '-', '.', '/', ')', ';', '=', '?', '_'];
+    const GREASE_VER: [&str; 3] = ["8", "99", "24"];
+    const PERMS: [[usize; 3]; 6] = [[0, 1, 2], [0, 2, 1], [1, 0, 2], [1, 2, 0], [2, 0, 1], [2, 1, 0]];
+    let grease_brand = format!(
+        "Not{}A{}Brand",
+        GREASE_CHARS[major % 11],
+        GREASE_CHARS[(major + 1) % 11]
+    );
+    let brands = [
+        (grease_brand, GREASE_VER[major % 3].to_string()),
+        ("Chromium".to_string(), major.to_string()),
+        ("Google Chrome".to_string(), major.to_string()),
+    ];
+    let p = PERMS[major % 6];
+    let sec_ch_ua = p
+        .iter()
+        .map(|&i| format!("\"{}\";v=\"{}\"", brands[i].0, brands[i].1))
+        .collect::<Vec<_>>()
+        .join(", ");
+    let platform = if ua.contains("Windows NT") {
+        "\"Windows\""
+    } else if ua.contains("Macintosh") {
+        "\"macOS\""
+    } else {
+        "\"Linux\""
+    };
+    (sec_ch_ua, platform.to_string())
+}
+
 impl ObscuraHttpClient {
     pub fn new() -> Self {
         Self::with_cookie_jar(Arc::new(CookieJar::new()))
@@ -407,50 +447,38 @@ impl ObscuraHttpClient {
             }
 
             let ua = self.user_agent.read().await.clone();
+            let (sec_ch_ua, sec_ch_ua_platform) = chrome_client_hints(&ua);
             let mut headers = HeaderMap::new();
+            // Chrome's top-level navigation header order. (reqwest appends
+            // accept-encoding/host after these, so accept-encoding lands after
+            // accept-language rather than before it; the rest matches Chrome.)
+            headers.insert(
+                HeaderName::from_static("sec-ch-ua"),
+                HeaderValue::from_str(&sec_ch_ua)
+                    .unwrap_or_else(|_| HeaderValue::from_static("\"Not:A-Brand\";v=\"99\", \"Google Chrome\";v=\"145\", \"Chromium\";v=\"145\"")),
+            );
+            headers.insert(HeaderName::from_static("sec-ch-ua-mobile"), HeaderValue::from_static("?0"));
+            headers.insert(
+                HeaderName::from_static("sec-ch-ua-platform"),
+                HeaderValue::from_str(&sec_ch_ua_platform)
+                    .unwrap_or_else(|_| HeaderValue::from_static("\"Windows\"")),
+            );
+            headers.insert(HeaderName::from_static("upgrade-insecure-requests"), HeaderValue::from_static("1"));
             headers.insert(USER_AGENT, HeaderValue::from_str(&ua).unwrap_or_else(|_| {
-                HeaderValue::from_static("Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/145.0.0.0 Safari/537.36")
+                HeaderValue::from_static("Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/145.0.0.0 Safari/537.36")
             }));
             headers.insert(
                 reqwest::header::ACCEPT,
                 HeaderValue::from_static("text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.7"),
             );
+            headers.insert(HeaderName::from_static("sec-fetch-site"), HeaderValue::from_static("none"));
+            headers.insert(HeaderName::from_static("sec-fetch-mode"), HeaderValue::from_static("navigate"));
+            headers.insert(HeaderName::from_static("sec-fetch-user"), HeaderValue::from_static("?1"));
+            headers.insert(HeaderName::from_static("sec-fetch-dest"), HeaderValue::from_static("document"));
             headers.insert(
                 reqwest::header::ACCEPT_LANGUAGE,
                 HeaderValue::from_static("en-US,en;q=0.9"),
             );
-            headers.insert(
-                HeaderName::from_static("sec-ch-ua"),
-                HeaderValue::from_static("\"Chromium\";v=\"145\", \"Not;A=Brand\";v=\"24\", \"Google Chrome\";v=\"145\""),
-            );
-            headers.insert(
-                HeaderName::from_static("sec-ch-ua-mobile"),
-                HeaderValue::from_static("?0"),
-            );
-            headers.insert(
-                HeaderName::from_static("sec-ch-ua-platform"),
-                HeaderValue::from_static("\"Linux\""),
-            );
-            headers.insert(
-                HeaderName::from_static("sec-fetch-dest"),
-                HeaderValue::from_static("document"),
-            );
-            headers.insert(
-                HeaderName::from_static("sec-fetch-mode"),
-                HeaderValue::from_static("navigate"),
-            );
-            headers.insert(
-                HeaderName::from_static("sec-fetch-site"),
-                HeaderValue::from_static("none"),
-            );
-            headers.insert(
-                HeaderName::from_static("sec-fetch-user"),
-                HeaderValue::from_static("?1"),
-            );
-            headers.insert(
-                HeaderName::from_static("upgrade-insecure-requests"),
-                HeaderValue::from_static("1"),
-            );
 
             let cookie_header = self.cookie_jar.get_cookie_header(&current_url);
             tracing::debug!(

crates/obscura-net/src/lib.rs

@@ -19,4 +19,7 @@ pub use encoding::{
 pub use robots::RobotsCache;
 pub use blocklist::is_blocked as is_tracker_blocked;
 #[cfg(feature = "stealth")]
-pub use wreq_client::{StealthHttpClient, STEALTH_USER_AGENT};
+pub use wreq_client::{
+    StealthHttpClient, STEALTH_NAVIGATOR_PLATFORM, STEALTH_UA_PLATFORM,
+    STEALTH_UA_PLATFORM_VERSION, STEALTH_USER_AGENT,
+};

crates/obscura-net/src/wreq_client.rs

@@ -19,7 +19,18 @@ use crate::client::{Response, ObscuraNetError};
 
 #[cfg(feature = "stealth")]
 pub const STEALTH_USER_AGENT: &str =
-    "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/145.0.0.0 Safari/537.36";
+    "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/145.0.0.0 Safari/537.36";
+
+// The wreq emulation (Profile::Chrome145, Platform::Windows) sends this exact
+// UA and sec-ch-ua-platform "Windows" on the wire. navigator has to report the
+// same identity, otherwise the TLS/HTTP layer and the JS layer disagree and a
+// site cross-checks the mismatch as a bot signal.
+#[cfg(feature = "stealth")]
+pub const STEALTH_NAVIGATOR_PLATFORM: &str = "Win32";
+#[cfg(feature = "stealth")]
+pub const STEALTH_UA_PLATFORM: &str = "Windows";
+#[cfg(feature = "stealth")]
+pub const STEALTH_UA_PLATFORM_VERSION: &str = "15.0.0";
 
 #[cfg(feature = "stealth")]
 pub struct StealthHttpClient {
@@ -38,7 +49,7 @@ impl StealthHttpClient {
     pub fn with_proxy(cookie_jar: Arc<CookieJar>, proxy_url: Option<&str>) -> Self {
         let emulation_opts = wreq_util::Emulation::builder()
             .profile(wreq_util::Profile::Chrome145)
-            .platform(wreq_util::Platform::Linux)
+            .platform(wreq_util::Platform::Windows)
             .build();
 
         let mut builder = wreq::Client::builder()
@@ -143,6 +154,85 @@ impl StealthHttpClient {
         Err(ObscuraNetError::TooManyRedirects(url.to_string()))
     }
 
+    /// One request with no redirect following, for scripted fetch()/XHR. Reads
+    /// the cookie jar for the Cookie header and stores Set-Cookie back into it,
+    /// so the caller only owns redirect hops and SSRF re-validation. Used in
+    /// stealth mode so JS-level requests carry the same Chrome TLS fingerprint
+    /// and client hints as the main navigation instead of the rustls ClientHello
+    /// that op_fetch_url would otherwise send (which bot managers read as a
+    /// non-browser script and reject, e.g. the AWS WAF challenge verify call).
+    pub async fn send_single(
+        &self,
+        method: &str,
+        url: &Url,
+        headers: &HashMap<String, String>,
+        body: &str,
+    ) -> Result<Response, ObscuraNetError> {
+        if let Some(host) = url.host_str() {
+            if crate::blocklist::is_blocked(host) {
+                tracing::debug!("Blocked tracker: {}", url);
+                return Ok(Response {
+                    status: 0,
+                    url: url.clone(),
+                    headers: HashMap::new(),
+                    body: Vec::new(),
+                    redirected_from: Vec::new(),
+                });
+            }
+        }
+
+        let req_method = method
+            .parse::<wreq::Method>()
+            .map_err(|e| ObscuraNetError::Network(format!("invalid method '{}': {}", method, e)))?;
+        let mut req = self.client.request(req_method, url.as_str());
+
+        let cookie_header = self.cookie_jar.get_cookie_header(url);
+        if !cookie_header.is_empty() {
+            req = req.header("cookie", &cookie_header);
+        }
+        for (k, v) in self.extra_headers.read().await.iter() {
+            req = req.header(k.as_str(), v.as_str());
+        }
+        for (k, v) in headers.iter() {
+            req = req.header(k.as_str(), v.as_str());
+        }
+        if !body.is_empty() {
+            req = req.body(body.to_string());
+        }
+
+        self.in_flight.fetch_add(1, std::sync::atomic::Ordering::Relaxed);
+        let resp = req.send().await.map_err(|e| {
+            self.in_flight.fetch_sub(1, std::sync::atomic::Ordering::Relaxed);
+            ObscuraNetError::Network(format!("{}: {}", url, e))
+        })?;
+        self.in_flight.fetch_sub(1, std::sync::atomic::Ordering::Relaxed);
+
+        let status = resp.status();
+        for val in resp.headers().get_all("set-cookie") {
+            if let Ok(s) = val.to_str() {
+                self.cookie_jar.set_cookie(s, url);
+            }
+        }
+        let response_headers: HashMap<String, String> = resp
+            .headers()
+            .iter()
+            .map(|(k, v)| (k.as_str().to_lowercase(), v.to_str().unwrap_or("").to_string()))
+            .collect();
+        let resp_body = resp
+            .bytes()
+            .await
+            .map_err(|e| ObscuraNetError::Network(format!("Failed to read body: {}", e)))?
+            .to_vec();
+
+        Ok(Response {
+            url: url.clone(),
+            status: status.as_u16(),
+            headers: response_headers,
+            body: resp_body,
+            redirected_from: Vec::new(),
+        })
+    }
+
     pub async fn set_extra_headers(&self, headers: HashMap<String, String>) {
         *self.extra_headers.write().await = headers;
     }