CVE-2021-22963: Fastify Fastify-Static

Medium severity, CVSS 6.1. EPSS: 1.2% chance of exploitation in the next 30 days.

A redirect vulnerability in the fastify-static module version < 4.2.4 allows remote attackers to redirect users to arbitrary websites via a double slash // followed by a domain: http://localhost:3000//google.com/%2e%2e.The issue shows up on all the fastify-static applications that set redirect: true option. By default, it is false.

Affected products

• Fastify Fastify-Static: before 4.2.4 (fixed in 4.2.4)

Published 2021-10-14. Last modified 2026-06-17.