{"id":"CVE-2026-34077","aliases":["GHSA-rxv8-25v2-qmq8"],"url":"https://o3.security/vulnerability/CVE-2026-34077","summary":"React Router vulnerable to Denial of Service via reflected user input in single-fetch","details":"A DoS vulnerability exists in the React Router v7 [Framework Mode](https://reactrouter.com/start/modes#framework), as well as Remix v2.9.0+ with [Single Fetch](https://v2.remix.run/docs/guides/single-fetch) enabled. In some scenarios the underlying serialization algorithm can become a bottleneck when encoding specific types of data into server responses.  Please upgrade to React Router v7.14.0 or later.\n\n> [!NOTE]\n> This does not impact your React Router application if you are using [Declarative Mode](https://reactrouter.com/start/modes#declarative) (`<BrowserRouter>`) or [Data Mode](https://reactrouter.com/start/modes#data) (`createBrowserRouter`/`<RouterProvider>`).","published":"2026-06-02T17:31:35.579Z","modified":"2026-08-12T03:51:34.605908710Z","cvss":{"score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},"epss":{"score":0.00294,"percentile":0.22086,"asOf":"2026-09-17"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"react-router","fixedVersion":"7.14.0"},{"ecosystem":"npm","name":"turbo-stream","fixedVersion":"3.0.0"}],"fix":{"url":"https://github.com/remix-run/react-router/commit/59811921d3c7d599077b8cadccdcd65a233165e0","label":"remix-run/react-router@5981192"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/34xxx/CVE-2026-34077.json"},{"type":"ADVISORY","url":"https://github.com/remix-run/react-router/security/advisories/GHSA-rxv8-25v2-qmq8"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-34077"},{"type":"WEB","url":"https://github.com/remix-run/react-router/commit/59811921d3c7d599077b8cadccdcd65a233165e0"},{"type":"WEB","url":"https://github.com/jacob-ebey/turbo-stream/blob/v2.4.1/src/flatten.ts#L175-L177"},{"type":"WEB","url":"https://github.com/jacob-ebey/turbo-stream/blob/v2.4.1/src/unflatten.ts#L185-L189"},{"type":"PACKAGE","url":"https://github.com/remix-run/react-router"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:34.605908710Z"}}