@fastify/static vulnerable to route guard bypass via encoded path separators
Impact
@fastify/static v9.1.0 and earlier decodes percent-encoded path separators (%2F) before filesystem resolution, but Fastify's router treats them as literal characters. This creates a routing mismatch: route guards on /admin/* do not match /admin%2Fsecret.html, but @fastify/static decodes it to /admin/secret.html and serves the file.
Applications that rely on route-based middleware or guards to protect files served by @fastify/static can be bypassed with encoded path separators.
Patches
Upgrade to @fastify/static >= 9.1.1.
Workarounds
None. Upgrade to the patched version.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | @fastify/static | >= 8.0.0, < 9.1.1 | 9.1.1 |
References
- https://github.com/fastify/fastify-static/security/advisories/GHSA-x428-ghpx-8j92
- https://github.com/fastify/middie/security/advisories/GHSA-cxrg-g7r8-w69p
- https://github.com/honojs/hono/security/advisories/GHSA-q5qw-h33p-qvwr
- https://nvd.nist.gov/vuln/detail/CVE-2026-6414
- https://cna.openjsf.org/security-advisories.html
- https://github.com/fastify/fastify-static
- CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N- Weakness (CWE)
CWE-177- Platform
- npm
- Package
@fastify/static- Disclosed
- 16.04.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-x428-ghpx-8j92 - CC BY 4.0
Vulnerability history: @fastify/static
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 4
- First → latest
- 04.2026 07.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 1
- Medium 3
Disclosures per year
- 2026: 4
-
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