Lack of protection against cookie tossing attacks in fastify-csrf

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

1. https://cheatsheetseries.owasp.org/cheatsheets/Cross-Site_Request_Forgery_Prevention_Cheat_Sheet.html
2. 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]