fastify/fastify-static · Security
@fastify/static vulnerable to route guard bypass via encoded path separators
- GHSA ID
- GHSA-x428-ghpx-8j92
- CVE ID
- CVE-2026-6414
- Severity
- medium
- Published
- Updated
- CVSS
- 5.9 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
- CVSS v3
- 5.9 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Description
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.
CWEs
- CWE-177 · Improper Handling of URL Encoding (Hex Encoding)
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/advisories/GHSA-x428-ghpx-8j92 ↗