# React Router: RSC Mode CSRF Bypass Allows Action Execution Before 400 Response

Advisory record · `GHSA-qwww-vcr4-c8h2`

- **Identifiers:** `GHSA-qwww-vcr4-c8h2`
- **State:** Confirmed
- **Severity:** CVSS 4.0, no score published
- **Critical:** No
- **Weakness (CWE):** [CWE-352](https://cwe.mitre.org/data/definitions/352.html)
- **Tags:** [Cross-site request forgery (CSRF)](https://agentprime.io/advisories/tag/csrf.md)
- **Published:** 24 Jul 2026
- **Updated:** 10 Sept 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 24 Jul 2026, 16:44 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `react-router` (npm): affected `>=7.12.0, <7.18.2 || >=8.0.0, <8.3.0`; fixed in `7.18.2`, `8.3.0`

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- Score not published, CVSS 4.0: `CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N`, from GitHub Advisory Database

- **CISA KEV:** Not listed.
- **EPSS:** No score.

## Timeline

- 22 Jul 2026, 16:23 UTC: [Published by the maintainers as a GitHub repository advisory](https://github.com/remix-run/react-router/security/advisories/GHSA-qwww-vcr4-c8h2)

## Sources

- [GitHub Advisory Database: GHSA-qwww-vcr4-c8h2](https://github.com/advisories/GHSA-qwww-vcr4-c8h2)
- [OSV: GHSA-qwww-vcr4-c8h2](https://osv.dev/vulnerability/GHSA-qwww-vcr4-c8h2)
- <https://github.com/remix-run/react-router/security/advisories/GHSA-qwww-vcr4-c8h2>
- <https://github.com/remix-run/react-router/pull/15353>
- <https://github.com/remix-run/react-router/commit/7a71c728ad116bd78699a258b2014ce9585729f5>
- <https://github.com/remix-run/react-router/commit/8ebd5df9932854547963e3255c8454e62430e05d>
- <https://github.com/remix-run/react-router>
- <https://github.com/remix-run/react-router/blob/main/CHANGELOG.md#v830>
- <https://github.com/remix-run/react-router/blob/v7/CHANGELOG.md#v7182>
- <https://github.com/remix-run/react-router/releases/tag/react-router%407.18.2>
- <https://github.com/remix-run/react-router/releases/tag/react-router@8.3.0>
- <http://github.com/remix-run/react-router/pull/15311>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-qwww-vcr4-c8h2>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/GHSA-qwww-vcr4-c8h2/>. Everything for agents: <https://agentprime.io/llms.txt>.