EUVD-2026-337318

fkie_cve-2026-34226

Happy DOM is a JavaScript implementation of a web browser without its graphical user interface. Versions prior to 20.8.9 may attach cookies from the current page origin (`window.location`) instead of the request target URL when `fetch(..., { credentials: "include" })` is used. This can leak cookies from origin A to destination B. Version 20.8.9 fixes the issue.

GHSA-w4gp-fjgq-3q4g — Happy DOM's fetch credentials include uses page-origin cookies instead of target-origin cookies

Affected: npm: happy-dom

### Summary `happy-dom` may attach cookies from the current page origin (`window.location`) instead of the request target URL when `fetch(..., { credentials: "include" })` is used. This can leak cookies from origin A to destination B.

### Details In [`packages/happy-dom/src/fetch/utilities/FetchRequestHeaderUtility.ts`](https://github.com/capricorn86/happy-dom/blob/f8d8cad41e9722fab9eefb9dfb3cca696462e908/packages/happy-dom/src/fetch/utilities/FetchRequestHeaderUtility.ts) (`getRequestHeaders()`), cookie selection is performed with `originURL`:

```ts const originURL = new URL(options.window.location.href); const isCORS = FetchCORSUtility.isCORS(originURL, options.request[PropertySymbol.url]); // ... const cookies = options.browserFrame.page.context.cookieContainer.getCookies( originURL, false ); ```

Here, `originURL` represents the page URL, not the request destination URL. For outgoing requests, cookie lookup should use the request URL (for example: `new URL(options.request[PropertySymbol.url])`).

### PoC Script Content

```javascript const http = require('http'); const dns = require('dns').promises; const { Browser } = require('happy-dom');

async function listen(server, host) { return new Promise((resolve) => server.listen(0, host, () => resolve(server.address().port))); }

async function run() { let observedCookieHeader = null; const pageHost = process.env.PAGE_HOST || 'a.127.0.0.1.nip.io'; const apiHost = process.env.API_HOST || 'b.127.0.0.1.nip.io';…

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EUVD-2026-337318

fkie_cve-2026-34226

GHSA-w4gp-fjgq-3q4g — Happy DOM's fetch credentials include uses page-origin cookies instead of target-origin cookies