diff --git a/packages/insomnia-smoke-test/fixtures/response-getbodybuffer-id-scope-collection.yaml b/packages/insomnia-smoke-test/fixtures/response-getbodybuffer-id-scope-collection.yaml
new file mode 100644
index 0000000000..f9f265138e
--- /dev/null
+++ b/packages/insomnia-smoke-test/fixtures/response-getbodybuffer-id-scope-collection.yaml
@@ -0,0 +1,83 @@
+type: collection.insomnia.rest/5.0
+schema_version: "5.1"
+name: response.getBodyBuffer id scope collection
+meta:
+  id: wrk_6c1d9f2a000000000000000000000010
+  created: 1751900000000
+  modified: 1751900000000
+collection:
+  - url: localhost:4010/echo
+    name: self
+    meta:
+      id: req_6c1d9f2a000000000000000000000011
+      created: 1751900000001
+      modified: 1751900000001
+      isPrivate: false
+      sortKey: -1751900000001
+    method: POST
+    body:
+      mimeType: text/plain
+      text: SELF-CONTENT-MARKER-7f3a9c
+    headers:
+      - name: Content-Type
+        value: text/plain
+    settings:
+      renderRequestBody: true
+      encodeUrl: true
+      followRedirects: global
+      cookies:
+        send: true
+        store: true
+      rebuildPath: true
+  - url: localhost:4010/echo
+    name: victim
+    meta:
+      id: req_6c1d9f2a000000000000000000000012
+      created: 1751900000002
+      modified: 1751900000002
+      isPrivate: false
+      sortKey: -1751900000002
+    method: POST
+    body:
+      mimeType: text/plain
+      text: VICTIM-CONTENT-MARKER-9c1e4b
+    headers:
+      - name: Content-Type
+        value: text/plain
+    settings:
+      renderRequestBody: true
+      encodeUrl: true
+      followRedirects: global
+      cookies:
+        send: true
+        store: true
+      rebuildPath: true
+  - url: http://127.0.0.1:4010/echo
+    name: Sandbox Probe
+    meta:
+      id: req_6c1d9f2a000000000000000000000013
+      created: 1751900000003
+      modified: 1751900000003
+      isPrivate: false
+      sortKey: -1751900000003
+    method: GET
+    body:
+      mimeType: text/plain
+      text: |
+        {% getbodybufferidprobe 'req_6c1d9f2a000000000000000000000011', 'req_6c1d9f2a000000000000000000000012' %}
+    headers:
+      - name: Content-Type
+        value: text/plain
+cookieJar:
+  name: Default Jar
+  meta:
+    id: jar_6c1d9f2a000000000000000000000014
+    created: 1751900000000
+    modified: 1751900000000
+environments:
+  name: Base Environment
+  meta:
+    id: env_6c1d9f2a000000000000000000000015
+    created: 1751900000000
+    modified: 1751900000000
+    isPrivate: false
diff --git a/packages/insomnia-smoke-test/tests/smoke/response-bodypath-id-cross-response-scope.test.ts b/packages/insomnia-smoke-test/tests/smoke/response-bodypath-id-cross-response-scope.test.ts
new file mode 100644
index 0000000000..312d752741
--- /dev/null
+++ b/packages/insomnia-smoke-test/tests/smoke/response-bodypath-id-cross-response-scope.test.ts
@@ -0,0 +1,137 @@
+import fs from 'node:fs';
+import path from 'node:path';
+
+import { expect, type Page } from '@playwright/test';
+
+import { loadFixture } from '../../playwright/paths';
+import { test } from '../../playwright/test';
+
+// response.getBodyBuffer sits behind the models.read capability, which is granted to every template
+// tag at baseline with no manifest declaration. When a caller supplies response._id, the handler
+// re-loads that response server-side and reads only its own bodyPath — ignoring whatever bodyPath the
+// caller supplied alongside it. This closes a residual gap: pairing a real id (satisfying the
+// pre-fix, bodyPath-only ownership check, which merely asks "does this bodyPath belong to *some*
+// response") with a *different*, real response's bodyPath used to still read that other response's
+// content (CROSS-TENANT-DB-ACCESS-FINDINGS.md Finding 5's write-up, closed by SEC-SERVICES-FIXES-AUDIT-PLAN.md
+// Item 1).
+
+const PLUGIN_NAME = 'insomnia-plugin-getbodybuffer-id-scope';
+const SELF_MARKER = 'SELF-CONTENT-MARKER-7f3a9c';
+const VICTIM_MARKER = 'VICTIM-CONTENT-MARKER-9c1e4b';
+
+// Installs a template tag with no manifest permissions that looks up its own response by id (via the
+// baseline-granted response.getLatestForRequestId) and its "victim" response by id, then calls
+// response.getBodyBuffer with its own real id paired with the victim's real bodyPath.
+const installIdScopeProbePlugin = (dataPath: string) => {
+  const pluginDir = path.join(dataPath, 'plugins', PLUGIN_NAME);
+  fs.mkdirSync(pluginDir, { recursive: true });
+  fs.writeFileSync(
+    path.join(pluginDir, 'package.json'),
+    JSON.stringify({ name: PLUGIN_NAME, version: '1.0.0', main: 'index.js', insomnia: {} }),
+  );
+  fs.writeFileSync(
+    path.join(pluginDir, 'index.js'),
+    `
+      module.exports.templateTags = [
+        {
+          name: 'getbodybufferidprobe',
+          displayName: 'GetBodyBuffer Id Probe',
+          description: 'Reads its own response by id while pairing it with a different, real response bodyPath',
+          args: [
+            { displayName: 'Self Request Id', type: 'string', defaultValue: '' },
+            { displayName: 'Victim Request Id', type: 'string', defaultValue: '' },
+          ],
+          async run(context, selfRequestId, victimRequestId) {
+            var selfResp = await context.util.models.response.getLatestForRequestId(selfRequestId, null);
+            var victimResp = await context.util.models.response.getLatestForRequestId(victimRequestId, null);
+            if (!selfResp || !victimResp) { return 'MISSING_RESPONSE'; }
+            var raw = await context.util.models.response.getBodyBuffer({ _id: selfResp._id, bodyPath: victimResp.bodyPath });
+            var bytes = (raw && raw.data) || [];
+            var out = '';
+            for (var i = 0; i < bytes.length; i++) { out += String.fromCharCode(bytes[i]); }
+            return out;
+          },
+        },
+      ];
+    `,
+  );
+};
+
+const clearPluginToast = async (page: Page) => {
+  await page.getByLabel('Import').waitFor();
+  await page.evaluate(() => localStorage.setItem('plugin-system-changes-toast-shown', 'true'));
+  const dismissButtons = page.getByRole('button', { name: 'Dismiss' });
+  await dismissButtons
+    .first()
+    .waitFor({ timeout: 3000 })
+    .catch(() => {});
+  const deadline = Date.now() + 5000;
+  while (Date.now() < deadline && (await dismissButtons.count()) > 0) {
+    await dismissButtons.first().click({ force: true, timeout: 500 }).catch(() => {});
+  }
+};
+
+// Enables the sandbox via the real Preferences → Scripting UI toggle, not a pre-set settings object.
+const enableSandbox = async (page: Page) => {
+  await page.getByTestId('settings-button').click();
+  const sandboxToggle = page.getByTestId('toggle-template-tag-sandbox');
+  await page.getByRole('tab', { name: 'Scripting' }).click();
+  await sandboxToggle.getByRole('switch').waitFor();
+  await sandboxToggle.click();
+  await expect.soft(sandboxToggle.getByRole('switch')).toBeChecked();
+  await page.locator('.app').press('Escape');
+  await expect.soft(page.getByTestId('toggle-template-tag-sandbox')).toBeHidden();
+};
+
+const sendRequestAndWaitForResponse = async (page: Page, insomnia: any, requestName: string) => {
+  await insomnia.navigationSidebar.clickRequestOrFolder(requestName);
+  await page.getByTestId('request-pane').getByRole('button', { name: 'Send' }).click();
+  await expect.soft(page.getByRole('button', { name: 'Cancel Request' })).toBeHidden({ timeout: 30_000 });
+};
+
+test('response.getBodyBuffer reads only the id-resolved response body, ignoring a paired other-response bodyPath', async ({
+  page,
+  app,
+  dataPath,
+  insomnia,
+}) => {
+  installIdScopeProbePlugin(dataPath);
+  await clearPluginToast(page);
+
+  const fixture = await loadFixture('response-getbodybuffer-id-scope-collection.yaml');
+  await app.evaluate(async ({ clipboard }, text) => clipboard.writeText(text), fixture);
+  await page.getByLabel('Import').click();
+  await page.locator('[data-test-id="import-from-clipboard"]').click();
+  await page.getByRole('button', { name: 'Scan' }).click();
+  await page.getByRole('dialog').getByRole('button', { name: 'Import' }).click();
+
+  await page.evaluate(() => (window as any).main.plugins.reloadPlugins());
+
+  // Persist two real, distinct responses so the probe tag has real ids/bodyPaths to reference.
+  await sendRequestAndWaitForResponse(page, insomnia, 'self');
+  await sendRequestAndWaitForResponse(page, insomnia, 'victim');
+
+  await insomnia.navigationSidebar.clickRequestOrFolder('Sandbox Probe');
+  await page.getByText('Body', { exact: true }).click();
+
+  await enableSandbox(page);
+
+  const readTagPreview = async (tagPrefix: string): Promise<string> => {
+    await page.locator(`[data-template^="${tagPrefix}"]`).click();
+    const modal = page.getByRole('dialog');
+    const preview = modal.getByLabel('Live Preview');
+    await expect.soft(preview).not.toHaveValue('rendering...');
+    const value = (await preview.inputValue()).trim();
+    await modal.getByRole('button', { name: 'Done' }).click();
+    await expect.soft(modal).toBeHidden();
+    return value;
+  };
+
+  // The just-toggled setting needs a moment to propagate to the main process before the tag runs in
+  // the sandbox — poll until it does, then assert the caller's own response content is returned, not
+  // the paired victim response's. The echo server wraps the body in a JSON envelope (method/headers/
+  // data/cookies), so check for the marker as a substring rather than an exact match.
+  await expect.poll(() => readTagPreview('{% getbodybufferidprobe'), { timeout: 20_000 }).toContain(SELF_MARKER);
+  const finalPreview = await readTagPreview('{% getbodybufferidprobe');
+  expect.soft(finalPreview).not.toContain(VICTIM_MARKER);
+});