CVE-2026-6414 Details
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.
A vulnerability exists in @fastify/static versions 8.0.0 through 9.1.0, where the package decodes percent-encoded path separators before resolving file paths, creating a mismatch with Fastify's routing that treats these characters literally. This inconsistency allows attackers to bypass route-based middleware or guards protecting files served by @fastify/static. For instance, a guard on a protected path can be evaded by encoding the path separator in the URL.
Upgrade to @fastify/static version 9.1.1 or later.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed Apr 16, 2026References to Advisories, Solutions, and Tools
By selecting these links, you will be leaving this site. These are references gathered from the official CVE record and are not endorsed by Volerion.
| URL | Source(s) | Tag(s) |
|---|---|---|
| https://cna.openjsf.org/security-advisories.html | openjs | Third Party Advisory |
| https://github.com/fastify/fastify-static/security/advisories/GHSA-x428-ghpx-8j92 | openjs | Vendor Advisory |
| https://github.com/fastify/middie/security/advisories/GHSA-cxrg-g7r8-w69p | openjs | Not Applicable |
| https://github.com/honojs/hono/security/advisories/GHSA-q5qw-h33p-qvwr | openjs | Not Applicable |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-177 | Improper Handling of URL Encoding (Hex Encoding) | openjs |
Affected Products
| Product | Versions |
|---|---|
| fastify fastify-static | >= 8.0.0, < 9.1.1 |
CPE
Remediation
| |
Change History
4 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jun 17, 2026 | CVE Modified | openjs |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| Apr 23, 2026 | Initial Analysis | [email protected] |
| Apr 16, 2026 | New CVE Received | openjs |