CVE-2026-33244

MEDIUM5.4EPSS 0.03%

React Router has stored XSS via unescaped Location header in prerendered redirect HTML

Published: 6/3/2026Modified: 6/3/2026
Also known as:GHSA-f22v-gfqf-p8f3

Description

When using React Router v7 [Framework Mode](https://reactrouter.com/start/modes#framework) with [Pre-rendering](https://reactrouter.com/how-to/pre-rendering) enabled, an improper neutralization of the HTTP `Location` header value can permit Cross-Site Scripting (XSS) in statically generated HTML files if the redirect location comes from an untrusted source. > [!NOTE] > 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>`).

Affected packages (1)

CVSS scores

SourceVersionSeverityVector
osvCVSS 3.1MEDIUM5.4CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

References (3)