Vulnerability 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.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Fastify | Fastify-Static | >= 8.0.0, < 9.1.1 |
Related Weaknesses (CWE)
References
- https://cna.openjsf.org/security-advisories.htmlThird Party Advisory
- https://github.com/fastify/fastify-static/security/advisories/GHSA-x428-ghpx-8j9Vendor 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
FAQ
What is CVE-2026-6414?
CVE-2026-6414 is a vulnerability with a CVSS score of 5.9 (MEDIUM). @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 a...
How severe is CVE-2026-6414?
CVE-2026-6414 has been rated MEDIUM with a CVSS base score of 5.9/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-6414?
Check the references section above for vendor advisories and patch information. Affected products include: Fastify Fastify-Static.