fix(bundler-plugins): Escape JSON in generated injection code (#25265)

`JSON.stringify` leaves HTML script delimiters intact, allowing
attacker-controlled injected values to break out if a consumer inlines
the generated bundle into HTML. Escape `<` in metadata, release names,
and build information so HTML parsing cannot reinterpret those values,
while preserving their exact JavaScript runtime values.

Fixes [code-scanning alert
#467](https://github.com/getsentry/sentry-javascript/security/code-scanning/467).

Co-authored-by: GPT-6 <codex@openai.com>

Author: msonnb

packages/bundler-plugins/src/core/utils.ts

@@ -308,6 +308,11 @@ export function determineReleaseName(): string | undefined {
   );
 }
 
+function stringifyForCodeInjection(value: unknown): string | undefined {
+  // Bundles may be inlined in HTML, where JSON quoting does not escape script tags or HTML comments.
+  return JSON.stringify(value)?.replace(/</g, '\\u003c');
+}
+
 /**
  * Generates code for the global injector which is responsible for setting the global
  * `SENTRY_RELEASE` & `SENTRY_BUILD_INFO` variables.
@@ -319,12 +324,12 @@ export function generateReleaseInjectorCode({
   release: string;
   injectBuildInformation: boolean;
 }): CodeInjection {
-  let code = `e.SENTRY_RELEASE={id:${JSON.stringify(release)}};`;
+  let code = `e.SENTRY_RELEASE={id:${stringifyForCodeInjection(release)}};`;
 
   if (injectBuildInformation) {
     const buildInfo = getBuildInformation();
 
-    code += `e.SENTRY_BUILD_INFO=${JSON.stringify(buildInfo)};`;
+    code += `e.SENTRY_BUILD_INFO=${stringifyForCodeInjection(buildInfo)};`;
   }
 
   return new CodeInjection(code);
@@ -335,7 +340,7 @@ export function generateModuleMetadataInjectorCode(metadata: any): CodeInjection
   // We are merging the metadata objects in case modules are bundled twice with the plugin
   // Use try-catch to avoid issues when bundlers rename global variables like 'window' to 'k'
   return new CodeInjection(
-    `e._sentryModuleMetadata=e._sentryModuleMetadata||{},e._sentryModuleMetadata[(new e.Error).stack]=function(e){for(var n=1;n<arguments.length;n++){var a=arguments[n];if(null!=a)for(var t in a)a.hasOwnProperty(t)&&(e[t]=a[t])}return e}({},e._sentryModuleMetadata[(new e.Error).stack],${JSON.stringify(
+    `e._sentryModuleMetadata=e._sentryModuleMetadata||{},e._sentryModuleMetadata[(new e.Error).stack]=function(e){for(var n=1;n<arguments.length;n++){var a=arguments[n];if(null!=a)for(var t in a)a.hasOwnProperty(t)&&(e[t]=a[t])}return e}({},e._sentryModuleMetadata[(new e.Error).stack],${stringifyForCodeInjection(
       metadata,
     )});`,
   );

packages/bundler-plugins/test/core/utils.test.ts

@@ -11,8 +11,10 @@ import {
 
 import childProcess from 'child_process';
 import fs from 'fs';
-import { describe, it, expect, test, vi } from 'vitest';
+import { afterEach, describe, it, expect, test, vi } from 'vitest';
 import path from 'node:path';
+import { runInNewContext } from 'node:vm';
+import { JSDOM } from 'jsdom';
 
 type PackageJson = Record<string, unknown>;
 
@@ -284,6 +286,49 @@ describe('generateModuleMetadataInjectorCode', () => {
   });
 });
 
+describe('code injection in HTML', () => {
+  afterEach(() => {
+    vi.restoreAllMocks();
+  });
+
+  it.each([
+    '</script><script>globalThis.injected = true</script>',
+    '</ScRiPt \n><script>globalThis.injected = true</script>',
+    '<!--<script>',
+    'quotes "\' and backslashes \\u003c with whitespace \n\r\t\u2028\u2029 and <>&',
+  ])('preserves injected values containing %j inside one script element', value => {
+    vi.spyOn(fs, 'readFileSync').mockReturnValueOnce(
+      JSON.stringify({ name: 'test-app', dependencies: { [value]: '1.0.0' } }),
+    );
+    const metadata = { [value]: { values: [value] } };
+    const injection = generateReleaseInjectorCode({ release: value, injectBuildInformation: true });
+    injection.append(generateModuleMetadataInjectorCode(metadata));
+    const code = injection.code();
+    const context: {
+      SENTRY_RELEASE?: { id: string };
+      SENTRY_BUILD_INFO?: { deps: string[]; depsVersions: Record<string, number>; nodeVersion: number };
+      _sentryModuleMetadata?: Record<string, unknown>;
+    } = {};
+
+    const dom = new JSDOM(`<script>${code}</script>`);
+    const scripts = dom.window.document.querySelectorAll('script');
+    dom.window.close();
+
+    expect(scripts).toHaveLength(1);
+    expect(scripts[0]?.textContent).toBe(code);
+
+    runInNewContext(code, context);
+
+    expect(context.SENTRY_RELEASE).toEqual({ id: value });
+    expect(context.SENTRY_BUILD_INFO).toEqual({
+      deps: [value],
+      depsVersions: {},
+      nodeVersion: Number(process.versions.node.split('.')[0]),
+    });
+    expect(Object.values(context._sentryModuleMetadata ?? {})).toEqual([metadata]);
+  });
+});
+
 describe('determineReleaseName', () => {
   it('runs `git rev-parse HEAD` with windowsHide so no console window flashes on Windows', () => {
     // Clear env so the function falls through the CI/git-provider checks to the