GHSA-rc4q-9m69-gqp8 is a medium-severity (CVSS 6.5) CWE-565 vulnerability in fastify-csrf. O3 Security confirms whether GHSA-rc4q-9m69-gqp8 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Lack of protection against cookie tossing attacks in fastify-csrf
Real-World Exposure
fastify-csrfReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.
Description
Impact
Users that used fastify-csrf with the "double submit" mechanism using cookies with an application deployed across multiple subdomains, e.g. "heroku"-style platform as a service.
Patches
Version 3.1.0 of the fastify-csrf fixes it. See https://github.com/fastify/fastify-csrf/pull/51 and https://github.com/fastify/csrf/pull/2.
The user of the module would need to supply a userInfo when generating the CSRF token to fully implement the protection on their end. This is needed only for applications hosted on different subdomains.
Workarounds
None available.
References
- https://cheatsheetseries.owasp.org/cheatsheets/Cross-Site_Request_Forgery_Prevention_Cheat_Sheet.html
- https://owasp.org/www-pdf-archive/David_Johansson-Double_Defeat_of_Double-Submit_Cookie.pdf
Credits
This vulnerability was found by Xhelal Likaj [email protected].
For more information
If you have any questions or comments about this advisory:
- Open an issue in fastify-csrf
- Email us at [email protected]
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | fastify-csrf | all versions | 3.1.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for fastify-csrf. 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 fastify-csrf to 3.1.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-rc4q-9m69-gqp8 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-rc4q-9m69-gqp8 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-rc4q-9m69-gqp8. 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-rc4q-9m69-gqp8 in your dependencies?
O3 detects GHSA-rc4q-9m69-gqp8 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.