What’s Vulnerable › Vulnerabilities

CVE-2021-22964

• Severity: high (CVSS 8.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.0% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2021-10-14 · updated 2026-06-17
• Weakness: CWE-400

Description

A redirect vulnerability in the `fastify-static` module version >= 4.2.4 and < 4.4.1 allows remote attackers to redirect Mozilla Firefox users to arbitrary websites via a double slash `//` followed by a domain: `http://localhost:3000//a//youtube.com/%2e%2e%2f%2e%2e`.A DOS vulnerability is possible if the URL contains invalid characters `curl --path-as-is "http://localhost:3000//^/.."`The issue shows up on all the `fastify-static` applications that set `redirect: true` option. By default, it is `false`.

Affected products

• https://github.com/fastify/fastify-static: from 4.2.4 before 4.4.1 — fixed in 4.4.1

How to fix

Upgrade to a fixed version: https://github.com/fastify/fastify-static 4.4.1. Check the vendor advisory for mitigations.

References

• https://hackerone.com/reports/1361804
• https://hackerone.com/reports/1361804

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