CVE-2026-6414

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 Vector

References

• https://cna.openjsf.org/security-advisories.html
• 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