CVE-2026-6414

Name: CVE-2026-6414
Creator: NVD / NIST
Published: 2026-04-16T13:16:52.243+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.9/10EPSS 0.40%

Last modified Jun 17, 2026

CVE-2026-6414 is a medium-severity vulnerability rated 5.9/10 on the CVSS scale. @fastify/static versions 8.0.0 through 9.1.0 decode percent-encoded path separators (%2F) before filesystem resolution, while Fastify's router treats them as literal characters. This mismatch allows attackers to bypass route-based middleware or guards that protect files served by @fastify/static. EPSS estimates a 0.40% chance of exploitation in the next 30 days.

Description

@fastify/static versions 8.0.0 through 9.1.0 decode percent-encoded path separators (%2F) before filesystem resolution, while Fastify's router treats them as literal characters. This mismatch allows attackers to bypass route-based middleware or guards that protect files served by @fastify/static. For example, a route guard on a protected path can be circumvented by encoding the path separator in the URL. Upgrade to @fastify/static 9.1.1 to fix this issue. There are no workarounds.

Metrics

CVSS 3.1

5.9/10

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

EPSS Probability

0.40%

31.6th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-177

Affected Software

Vendor	Product	Versions
Fastify	Fastify-Static	>= 8.0.0, < 9.1.1

References

https://cna.openjsf.org/security-advisories.htmlThird Party Advisory
https://github.com/fastify/fastify-static/security/advisories/GHSA-x428-ghpx-8j92Vendor Advisory
https://github.com/fastify/middie/security/advisories/GHSA-cxrg-g7r8-w69pNot Applicable
https://github.com/honojs/hono/security/advisories/GHSA-q5qw-h33p-qvwrNot Applicable

Timeline

Published: Apr 16, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-6414?

How severe is CVE-2026-6414?

CVE-2026-6414 has a CVSS score of 5.9/10 (MEDIUM severity). The EPSS model estimates a 0.40% probability of exploitation in the next 30 days.

How do I fix CVE-2026-6414?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-6414?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST