EUVD-2026-23227
GHSA-x428-ghpx-8j92
Severity by source
AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Primary rating from NVD.
CVSS VectorNVD
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Lifecycle Timeline
4Blast Radius
ecosystem impact- 1 npm packages depend on @fastify/static (1 direct, 0 indirect)
Ecosystem-wide dependent count for version 8.0.0.
DescriptionCVE.org
@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.
Analysis
@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.
More in Fastify Static
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A redirect vulnerability in the fastify-static module version < 4.2.4 allows remote attackers to redirect users to arbit
Same technique Authentication Bypass
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External POC / Exploit Code
Leaving vuln.today