@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.
History

Thu, 16 Apr 2026 19:00:00 +0000

Type Values Removed Values Added
First Time appeared Fastify
Fastify fastify-static
Vendors & Products Fastify
Fastify fastify-static

Thu, 16 Apr 2026 14:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Thu, 16 Apr 2026 13:15:00 +0000

Type Values Removed Values Added
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.
Title @fastify/static vulnerable to route guard bypass via encoded path separators
Weaknesses CWE-177
References
Metrics cvssV3_1

{'score': 5.9, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: openjs

Published: 2026-04-16T13:09:03.526Z

Updated: 2026-04-16T13:48:52.393Z

Reserved: 2026-04-15T23:37:33.949Z

Link: CVE-2026-6414

cve-icon Vulnrichment

Updated: 2026-04-16T13:48:41.093Z

cve-icon NVD

Status : Received

Published: 2026-04-16T13:16:52.243

Modified: 2026-04-16T13:16:52.243

Link: CVE-2026-6414

cve-icon Redhat

No data.