diff --git a/src/components/session/authenticatedRequest.vue b/src/components/session/authenticatedRequest.vue
index a394c8ae..81cff26d 100644
--- a/src/components/session/authenticatedRequest.vue
+++ b/src/components/session/authenticatedRequest.vue
@@ -2,6 +2,7 @@
 import axios from 'axios'
 import { enqueueRequest } from "@/services/requestQueue.js";
 import { buildCurrentReleaseHeaders, resolveReleaseApiUrl } from "@/services/releaseTimeline.js";
+import { isTrustedReleaseUrl } from "@/services/releaseTrust.js";
 
 /**
  * Get the selected customer number for X-Customer-Number header (used by subusers)
@@ -18,22 +19,24 @@ export const authenticatedRequest = (url, method, data, catchCallable = null, th
     //throw new Error('No token was found, unable to make authenticated request');
   }
   
+  const requestUrl = resolveReleaseApiUrl(url);
+  const canSendCredentials = isTrustedReleaseUrl(requestUrl);
+
   // Build headers
   const headers = {
     ...buildCurrentReleaseHeaders(),
   };
-  if (token && token.length > 0) {
+  if (canSendCredentials && token && token.length > 0) {
     headers.Authorization = `Bearer ${token}`;
   }
   
   // Add X-Customer-Number header if subuser has selected a grant
   const isSubuser = localStorage.getItem('is_subuser') === 'true';
   const selectedCustomerNumber = getSelectedCustomerNumber();
-  if (isSubuser && selectedCustomerNumber) {
+  if (canSendCredentials && isSubuser && selectedCustomerNumber) {
     headers['X-Customer-Number'] = selectedCustomerNumber;
   }
   
-  const requestUrl = resolveReleaseApiUrl(url);
   return enqueueRequest(
     () => axios({
       method,
diff --git a/src/config.js b/src/config.js
index c08cac00..2f4b2910 100644
--- a/src/config.js
+++ b/src/config.js
@@ -29,6 +29,7 @@ const normalizeReleaseSource = (value) => {
 };
 export const RELEASE_SOURCE_ENV = String(import.meta.env.VITE_RELEASE_SOURCE || "").trim().toLowerCase();
 export const RELEASE_SOURCE = normalizeReleaseSource(RELEASE_SOURCE_ENV);
+export const DEFAULT_LEGACY_API_URL = "https://api.truckwash.io";
 export const DEFAULT_PUBLIC_GATEWAY_API_URL = "https://api-v2.truckwash.io";
 export const DEFAULT_STABLE_API_URL = `${DEFAULT_PUBLIC_GATEWAY_API_URL}/master/api`;
 
@@ -50,6 +51,10 @@ export const RELEASE_MANAGER_CONTROL_API_FALLBACK_URLS = String(
   .split(",")
   .map((url) => normalizeApiUrl(url.trim()))
   .filter(Boolean);
+export const RELEASE_TRUSTED_ORIGINS = String(import.meta.env.VITE_RELEASE_TRUSTED_ORIGINS || "")
+  .split(",")
+  .map((origin) => origin.trim().replace(/\/+$/, ""))
+  .filter(Boolean);
 
 // Allowed origins
 export const ALLOWED_ORIGINS = [
diff --git a/src/services/releaseBootstrap.js b/src/services/releaseBootstrap.js
index bac40976..1aa95fe1 100644
--- a/src/services/releaseBootstrap.js
+++ b/src/services/releaseBootstrap.js
@@ -1,5 +1,6 @@
 import { API_URL, IS_DEV, RELEASE_MANAGER_CONTROL_API_URL, RELEASE_SOURCE, RELEASE_SOURCE_ENV } from "@/config.js";
 import { buildReleaseHeaders } from "@/services/releaseHeaders.js";
+import { isTrustedReleaseUrl, sameOriginReleaseUrl } from "@/services/releaseTrust.js";
 
 export const RELEASE_RUNTIME_GLOBAL_KEY = "__TRUCKWASH_RELEASE_RUNTIME__";
 export const RELEASE_CHANNEL_SELECTION_STORAGE_KEY = "release_channel_selected_slug";
@@ -172,7 +173,8 @@ export const fetchReleaseRuntime = async ({
 
 const runtimeFrontendBaseUrl = (runtime = {}) => {
   const urls = runtime?.urls && typeof runtime.urls === "object" ? runtime.urls : {};
-  return normalizeBaseUrl(runtime?.frontend_base_url || urls.frontend_base_url || "");
+  const frontendBaseUrl = normalizeBaseUrl(runtime?.frontend_base_url || urls.frontend_base_url || "");
+  return isTrustedReleaseUrl(frontendBaseUrl, { allowRelative: false }) ? frontendBaseUrl : "";
 };
 
 const runtimeChannel = (runtime = {}) => runtime?.channel || {};
@@ -190,8 +192,14 @@ export const shouldLoadRemoteRelease = (runtime = {}) => {
 export const releaseEntryUrl = (frontendBaseUrl) =>
   new URL(RELEASE_ENTRY_FILENAME, `${normalizeBaseUrl(frontendBaseUrl)}/`).href;
 
-const resolveReleaseAssetUrl = (frontendBaseUrl, value) =>
-  new URL(String(value || "").replace(/^\/+/, ""), `${normalizeBaseUrl(frontendBaseUrl)}/`).href;
+const resolveReleaseAssetUrl = (frontendBaseUrl, value) => {
+  const baseUrl = normalizeBaseUrl(frontendBaseUrl);
+  const resolvedUrl = new URL(String(value || "").replace(/^\/+/, ""), `${baseUrl}/`).href;
+  if (!sameOriginReleaseUrl(resolvedUrl, baseUrl)) {
+    throw new Error("Release entry asset URL is not on the trusted release frontend origin.");
+  }
+  return resolvedUrl;
+};
 
 export const loadRemoteReleaseEntry = async ({
   runtime,
@@ -200,6 +208,9 @@ export const loadRemoteReleaseEntry = async ({
   importModule = (url) => import(/* @vite-ignore */ url),
 } = {}) => {
   const frontendBaseUrl = runtimeFrontendBaseUrl(runtime);
+  if (!frontendBaseUrl) {
+    throw new Error("Release frontend URL is not trusted.");
+  }
   const response = await fetchFn(releaseEntryUrl(frontendBaseUrl), {
     method: "GET",
     cache: "no-store",
diff --git a/src/services/releaseTimeline.js b/src/services/releaseTimeline.js
index edf4b5dd..cb5247f0 100644
--- a/src/services/releaseTimeline.js
+++ b/src/services/releaseTimeline.js
@@ -1,5 +1,6 @@
 import { reactive, readonly } from "vue";
 import { API_URL } from "@/config.js";
+import { isTrustedReleaseUrl } from "@/services/releaseTrust.js";
 import { buildReleaseHeaders, RELEASE_TRACE_STORAGE_KEY } from "@/services/releaseHeaders.js";
 
 const TRACE_STORAGE_KEY = RELEASE_TRACE_STORAGE_KEY;
@@ -97,9 +98,9 @@ const normalizeReadinessMissingValues = (missing = []) =>
     )
   );
 
-const normalizeRuntimeBaseUrl = (value) => {
+const normalizeRuntimeBaseUrl = (value, { allowRelative = true } = {}) => {
   const raw = String(value || "").trim().replace(/\/+$/, "");
-  if (!raw) {
+  if (!raw || !isTrustedReleaseUrl(raw, { allowRelative })) {
     return null;
   }
   if (raw.startsWith("/") && !raw.startsWith("//")) {
@@ -114,7 +115,9 @@ const normalizeRuntimeBaseUrl = (value) => {
 const runtimeUrls = (runtime = {}) => {
   const urls = runtime?.urls && typeof runtime.urls === "object" ? runtime.urls : {};
   return {
-    frontendBaseUrl: normalizeRuntimeBaseUrl(runtime.frontend_base_url ?? urls.frontend_base_url),
+    frontendBaseUrl: normalizeRuntimeBaseUrl(runtime.frontend_base_url ?? urls.frontend_base_url, {
+      allowRelative: false,
+    }),
     apiBaseUrl: normalizeRuntimeBaseUrl(runtime.api_base_url ?? urls.api_base_url),
   };
 };
@@ -421,7 +424,9 @@ const firstFilledString = (...values) => {
 const releaseRuntimeUrlsForDisplay = (runtime = {}) => {
   const urls = isPlainRecord(runtime?.urls) ? runtime.urls : {};
   return {
-    frontend: normalizeRuntimeBaseUrl(runtime.frontendBaseUrl ?? runtime.frontend_base_url ?? urls.frontend_base_url),
+    frontend: normalizeRuntimeBaseUrl(runtime.frontendBaseUrl ?? runtime.frontend_base_url ?? urls.frontend_base_url, {
+      allowRelative: false,
+    }),
     api: normalizeRuntimeBaseUrl(runtime.apiBaseUrl ?? runtime.api_base_url ?? urls.api_base_url),
   };
 };
diff --git a/src/services/releaseTrust.js b/src/services/releaseTrust.js
new file mode 100644
index 00000000..f10fca8f
--- /dev/null
+++ b/src/services/releaseTrust.js
@@ -0,0 +1,69 @@
+import {
+  ALLOWED_ORIGINS,
+  API_URL,
+  DEFAULT_LEGACY_API_URL,
+  DEFAULT_PUBLIC_GATEWAY_API_URL,
+  DEFAULT_STABLE_API_URL,
+  RELEASE_MANAGER_CONTROL_API_URL,
+  RELEASE_PUBLIC_GATEWAY_API_URL,
+  RELEASE_TRUSTED_ORIGINS,
+} from "@/config.js";
+
+const normalizeOrigin = (value) => {
+  const raw = String(value || "").trim();
+  if (!raw) {
+    return "";
+  }
+  try {
+    return new URL(raw).origin;
+  } catch {
+    return "";
+  }
+};
+
+const browserOrigin = () => {
+  if (typeof window !== "undefined" && window.location?.origin) {
+    return window.location.origin;
+  }
+  return "";
+};
+
+const configuredTrustedOrigins = () =>
+  [
+    browserOrigin(),
+    ...ALLOWED_ORIGINS,
+    ...RELEASE_TRUSTED_ORIGINS,
+    API_URL,
+    RELEASE_MANAGER_CONTROL_API_URL,
+    RELEASE_PUBLIC_GATEWAY_API_URL,
+    DEFAULT_LEGACY_API_URL,
+    DEFAULT_PUBLIC_GATEWAY_API_URL,
+    DEFAULT_STABLE_API_URL,
+  ]
+    .map(normalizeOrigin)
+    .filter(Boolean);
+
+export const trustedReleaseOrigins = () => Array.from(new Set(configuredTrustedOrigins()));
+
+export const isTrustedReleaseOrigin = (value) => {
+  const origin = normalizeOrigin(value);
+  return Boolean(origin) && trustedReleaseOrigins().includes(origin);
+};
+
+export const isRelativeReleaseUrl = (value) => {
+  const raw = String(value || "").trim();
+  return Boolean(raw) && raw.startsWith("/") && !raw.startsWith("//");
+};
+
+export const isTrustedReleaseUrl = (value, { allowRelative = true } = {}) => {
+  if (allowRelative && isRelativeReleaseUrl(value)) {
+    return true;
+  }
+  return isTrustedReleaseOrigin(value);
+};
+
+export const sameOriginReleaseUrl = (value, expectedBaseUrl) => {
+  const resolvedOrigin = normalizeOrigin(value);
+  const expectedOrigin = normalizeOrigin(expectedBaseUrl);
+  return Boolean(resolvedOrigin && expectedOrigin && resolvedOrigin === expectedOrigin);
+};
diff --git a/tests/unit/authenticated-request.spec.js b/tests/unit/authenticated-request.spec.js
index 48687819..7db2a6db 100644
--- a/tests/unit/authenticated-request.spec.js
+++ b/tests/unit/authenticated-request.spec.js
@@ -11,6 +11,7 @@ vi.mock("axios", () => ({
 }));
 
 import { authenticatedRequest } from "@/components/session/authenticatedRequest.vue";
+import { __resetReleaseTimelineForTests, configureReleaseRuntime } from "@/services/releaseTimeline.js";
 import {
   __configureRequestQueueForTests,
   __resetRequestQueueForTests,
@@ -43,6 +44,7 @@ describe("authenticatedRequest", () => {
   beforeEach(() => {
     axiosMock.mockReset();
     __resetRequestQueueForTests();
+    __resetReleaseTimelineForTests();
     __configureRequestQueueForTests({
       maxConcurrentGet: 1,
       maxConcurrentOther: 1,
@@ -102,6 +104,26 @@ describe("authenticatedRequest", () => {
     expect(catchCallable).toHaveBeenCalledWith(error);
   });
 
+  it("does not send bearer credentials to untrusted absolute request URLs", async () => {
+    const response = { status: 200, data: { ok: true } };
+    axiosMock.mockResolvedValueOnce(response);
+    localStorage.setItem("is_subuser", "true");
+    localStorage.setItem("selected_customer_number", "1234");
+    configureReleaseRuntime({ api_base_url: "https://attacker.example/api" });
+
+    await authenticatedRequest("https://attacker.example/api/orders", "GET");
+
+    expect(axiosMock).toHaveBeenCalledWith(
+      expect.objectContaining({
+        url: "https://attacker.example/api/orders",
+        headers: expect.not.objectContaining({
+          Authorization: "Bearer token",
+          "X-Customer-Number": 1234,
+        }),
+      })
+    );
+  });
+
   it("queues requests and executes them sequentially", async () => {
     const first = createDeferred();
     const second = createDeferred();
diff --git a/tests/unit/release-bootstrap.spec.js b/tests/unit/release-bootstrap.spec.js
index 2c6a3cd0..96421ee0 100644
--- a/tests/unit/release-bootstrap.spec.js
+++ b/tests/unit/release-bootstrap.spec.js
@@ -163,6 +163,18 @@ describe("release bootstrap", () => {
     expect(shouldLoadRemoteRelease(null)).toBe(false);
   });
 
+  it("does not load a remote release from an untrusted frontend origin", () => {
+    const runtime = {
+      channel: { slug: "canary", default_channel: false },
+      availability: { configured: true },
+      urls: {
+        frontend_base_url: "https://attacker.example/canary/frontend",
+      },
+    };
+
+    expect(shouldLoadRemoteRelease(runtime)).toBe(false);
+  });
+
   it("loads a non-default release entry without changing the browser URL", async () => {
     const runtime = {
       channel: { slug: "canary", default_channel: false },
@@ -241,6 +253,25 @@ describe("release bootstrap", () => {
     });
   });
 
+  it("rejects release entry assets outside the frontend origin", async () => {
+    const fetchFn = vi.fn(async () => ({
+      ok: true,
+      json: async () => ({
+        entry: "https://attacker.example/assets/index-canary.js",
+        css: [],
+      }),
+    }));
+    const importModule = vi.fn(async () => ({}));
+    const runtime = {
+      frontend_base_url: "https://api-v2.truckwash.io/canary/frontend",
+    };
+
+    await expect(loadRemoteReleaseEntry({ runtime, fetchFn, importModule, documentRef: document })).rejects.toThrow(
+      "Release entry asset URL is not on the trusted release frontend origin."
+    );
+    expect(importModule).not.toHaveBeenCalled();
+  });
+
   it("injects release entry CSS only once", async () => {
     const fetchFn = vi.fn(async () => ({
       ok: true,
diff --git a/tests/unit/release-timeline.spec.js b/tests/unit/release-timeline.spec.js
index 6ec05d38..987e464c 100644
--- a/tests/unit/release-timeline.spec.js
+++ b/tests/unit/release-timeline.spec.js
@@ -212,6 +212,26 @@ describe("release timeline runtime", () => {
     expect(resolveReleaseApiUrl("/orders")).toBe("https://api-v2.truckwash.io/canary/api/orders");
   });
 
+  it("ignores untrusted runtime frontend and API URLs", () => {
+    configureReleaseRuntime({
+      trace_id: "trace-untrusted",
+      channel: { slug: "canary", name: "Canary" },
+      versions: {
+        frontend: { version_label: "frontend-canary" },
+        api: { version_label: "api-canary" },
+        bundle_id: 31,
+      },
+      urls: {
+        frontend_base_url: "https://attacker.example/frontend",
+        api_base_url: "https://attacker.example/api",
+      },
+    });
+
+    expect(releaseRuntimeState.frontendBaseUrl).toBeNull();
+    expect(releaseRuntimeState.apiBaseUrl).toBeNull();
+    expect(resolveReleaseApiUrl("/orders")).not.toBe("https://attacker.example/api/orders");
+  });
+
   it("keeps same-origin release API URLs visible in the session summary", () => {
     configureReleaseRuntime({
       trace_id: "trace-local-api",