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. 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.
Scoring
- Severity
- MEDIUM
- CVSS base score
- 5.9
- CVSS vector
- CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
- EPSS probability
- 0.41%
- CWE
- CWE-177
- Published
- 2026-04-16
- Last modified
- 2026-04-16
Affected products
- @fastify/static @fastify/static
- @fastify/static @fastify/static
Weakness type
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