medium5.9
CVE-2026-6414
@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 l…
Impact
@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 packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| npm | @fastify/static | >= 8.0.0, <= 9.1.0 | 9.1.1 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Fastify | Fastify-Static | from 8.0.0 before 9.1.1 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-x428-ghpx-8j92
- 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