React Router has stored XSS via unescaped Location header in prerendered redirect HTML (CVE-2026-33244) | HOL Guard CVE

Medium · CVSS 5.4CVE-2026-33244GHSA-F22V-GFQF-P8F3

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

Answer in brief

CVE-2026-33244 records a Medium severity (CVSS 5.4) vulnerability in React Router has stored XSS via unescaped Location header in prerendered redirect HTML. The current sources do not mark it as known exploited. The current feed maps react-router (npm). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Jun 3, 2026Updated Sep 8, 2026Source checked Sep 8, 2026First seen by HOL Sep 8, 2026Material review Sep 8, 2026

Upstream Advisory

Key facts

Risk: Medium · CVSS 5.4
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

CVSS is 5.4. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps react-router (npm). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
react-routernpm	>=7.5.1,<7.13.2	7.13.2

Recommended response

Check inventory. Check lockfiles and deployed manifests for react-router.
Review the reported fix. Update react-router to 7.13.2 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Jun 3, 2026
Evidence: source:ghsa:source_dates:source-dates:record
Source modified
Sep 8, 2026
Evidence: source:ghsa:source_dates:source-dates:record
First seen by HOL
Sep 8, 2026

Sources and claim methodology

Upstream source 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>`).

Quoted source text, attributed separately from HOL analysis.