# CVE-2026-53667: React Router: RSCErrorHandler Missing Protocol Validation (XSS)

> Attackers can execute scripts via untrusted redirects in React Router when using unstable RSC APIs, requiring an upgrade to the latest version.

- **Severity:** Medium 6.9 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 27 Jul 2026
- **Updated:** 28 Jul 2026
- **Also known as:** GHSA-h8fp-f39c-q6mh, ROOT-APP-NPM-CVE-2026-53667

## What is CVE-2026-53667?

CVE-2026-53667 is a medium-severity cross-site scripting vulnerability in remix-run react-router, published on 27 Jul 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

React Router is a router for React. In versions 7.11.0 through 7.17.0, the RSCErrorHandler is missing protocol validation, allowing for redirects from untrusted sources. This issue is a follow up to CVE-2026-53667, and only affects consuming applications if they are using the unstable RSC APIs. This issue has been fixed in version 7.18.0.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-53667?

2 open source packages ship an affected version, including react-router. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `react-router` | npm | From 7.11.0 | 7.18.0 |
| `react-router` | npm | From 7.11.0 | 7.18.0 |

Products: Shopify React-Router.

## How do I fix CVE-2026-53667?

Upgrade react-router to 7.18.0 or later.

## Is CVE-2026-53667 being exploited?

There is no known exploitation of CVE-2026-53667 in the wild and no public exploit code.

## Other vulnerabilities in remix-run react-router

- [CVE-2026-55685](https://insights.sbomify.com/CVE-2026-55685/): React Router: Unauthenticated Denial of Service via Inefficient Route Matching (high 8.7)
- [CVE-2026-21884](https://insights.sbomify.com/CVE-2026-21884/): React Router SSR XSS in ScrollRestoration (high 8.2)
- [CVE-2026-42211](https://insights.sbomify.com/CVE-2026-42211/): React Router's vendored turbo-stream v2 allows arbitrary constructor invocation via TYPE_ERROR deserialization leading to Unauth RCE (high 8.1)
- [CVE-2026-33245](https://insights.sbomify.com/CVE-2026-33245/): React Router vulnerable to XSS in unstable RSC redirect handling via javascript: redirect targets (high 8.0)
- [CVE-2026-22029](https://insights.sbomify.com/CVE-2026-22029/): React Router vulnerable to XSS via Open Redirects (high 8.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-53667 and fix it if it is affected.

What it is: CVE-2026-53667 is a medium-severity cross-site scripting vulnerability in remix-run react-router, published on 27 Jul 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-53667 in the wild and no public exploit code.

Affected packages and fixed versions:
- react-router (npm): affected from 7.11.0; fixed in 7.18.0
- react-router (npm): affected from 7.11.0; fixed in 7.18.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-53667/ (Markdown: https://insights.sbomify.com/CVE-2026-53667/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-53667
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-53667
- OSV: https://osv.dev/vulnerability/CVE-2026-53667

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-53667/
Summaries are generated and may contain mistakes; the official description above is the record.