What is CVE-2026-6414?

CVE-2026-6414 is a medium-severity vulnerability in Fastify 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 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: 0.004 (32.1th 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 Fastify-static
@Fastify/static — versions 8.0.0, 9.1.1

Weakness classification (CWE)

CWE-177

References

ce714d77-add3-4f53-aff5-83d477b104bb (Not Applicable)
ce714d77-add3-4f53-aff5-83d477b104bb (Not Applicable)
ce714d77-add3-4f53-aff5-83d477b104bb (Vendor Advisory)
ce714d77-add3-4f53-aff5-83d477b104bb (Third Party Advisory)

Frequently asked questions

What is CVE-2026-6414?: CVE-2026-6414 is a medium-severity vulnerability in Fastify 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.