# CVE-2026-6414

## Summary

- **CVE ID:** CVE-2026-6414
- **Severity:** MEDIUM
- **CVSS Score:** 5.9 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N)
- **CWE:** CWE-177
- **Published:** Apr 16, 2026
- **Last Modified:** Apr 16, 2026

## 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.

## Affected Products

- @fastify/static — @fastify/static (8.0.0)
- @fastify/static — @fastify/static (9.1.1)

## References

- [CNA](https://github.com/fastify/middie/security/advisories/GHSA-cxrg-g7r8-w69p)
- [CNA](https://github.com/honojs/hono/security/advisories/GHSA-q5qw-h33p-qvwr)
- [CNA](https://github.com/fastify/fastify-static/security/advisories/GHSA-x428-ghpx-8j92)
- [CNA](https://cna.openjsf.org/security-advisories.html)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.41%
- **EPSS Percentile:** 34.6

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._