What is CVE-2026-6414?

CVE-2026-6414 is a medium-severity vulnerability in @Fastify/static, classified under CWE-177. CVSS score: 5.9/10. Published 2026-04-16.

How severe is CVE-2026-6414?

Medium severity. CVSS v3 base score is 5.9 out of 10.

Vulnerability in @Fastify/static

CVE-2026-6414

@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 middlewa…

EPSS: 0.000 (3.7th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N.

Affected products

@Fastify/static — versions 8.0.0, 9.1.1

Weakness classification (CWE)

CWE-177

References

github.com/fastify/middie/security/advisories/GHSA-cxrg-g7r8-w69p
github.com/honojs/hono/security/advisories/GHSA-q5qw-h33p-qvwr
github.com/fastify/fastify-static/security/advisories/GHSA-x428-ghpx-8j92
cna.openjsf.org/security-advisories.html

Frequently asked questions

What is CVE-2026-6414?: CVE-2026-6414 is a medium-severity vulnerability in @Fastify/static, classified under CWE-177. CVSS score: 5.9/10. Published 2026-04-16.
How severe is CVE-2026-6414?: Medium severity. CVSS v3 base score is 5.9 out of 10.