CVE-2021-29624: Fastify Fastify-Csrf

Medium severity, CVSS 6.5. EPSS: 0.8% chance of exploitation in the next 30 days.

fastify-csrf is an open-source plugin helps developers protect their Fastify server against CSRF attacks. Versions of fastify-csrf prior to 3.1.0 have a "double submit" mechanism using cookies with an application deployed across multiple subdomains, e.g. "heroku"-style platform as a service. Version 3.1.0 of the fastify-csrf fixes it. the vulnerability. 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.

Affected products

• Fastify Fastify-Csrf: before 3.1.0 (fixed in 3.1.0)

Published 2021-05-19. Last modified 2026-06-17.