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 literal characters.
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No exploitation reported and no EPSS estimate yet.
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@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
- 5.9 MEDIUM (v3.1, NVD)CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
- Weakness (CWE)
- CWE-177
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Not given
- NVD analysis
- Analyzed
- Record last updated
- Jun 17, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
fastify fastify-static fastify:fastify-static | from 8.0.0 before 9.1.1 | NVD |
References
- https://cna.openjsf.org/security-advisories.htmlthird-party-advisory
- https://github.com/fastify/fastify-static/security/advisories/GHSA-x428-ghpx-8j92vendor-advisory
- https://github.com/fastify/middie/security/advisories/GHSA-cxrg-g7r8-w69pnot-applicable
- https://github.com/honojs/hono/security/advisories/GHSA-q5qw-h33p-qvwrnot-applicable
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.