CVEvulnerability

CVE-2026-33804

9.1 CRITICAL Published 2026-04-16 Modified 2026-06-17 Official page ↗
Status
Analyzed
Published
2026-04-16
Last modified
2026-06-17
Assigner
ce714d77-add3-4f53-aff5-83d477b104bb
CVSS 3.1 (ce714d77-add3-4f53-aff5-83d477b104bb)
7.4 HIGH — CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
CVSS 3.1 ([email protected])
9.1 CRITICAL — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Weaknesses
CWE-436

Description

@fastify/middie versions 9.3.1 and earlier are vulnerable to middleware bypass when the deprecated Fastify ignoreDuplicateSlashes option is enabled. The middleware path matching logic does not account for duplicate slash normalization performed by Fastify's router, allowing requests with duplicate slashes to bypass middleware authentication and authorization checks. This only affects applications using the deprecated ignoreDuplicateSlashes option. Upgrade to @fastify/middie 9.3.2 to fix this issue. There are no workarounds other than disabling the ignoreDuplicateSlashes option.

Affected configurations

• fastify fastify\/middie (< 9.3.2)

Related

Weakness · CWE (1)

  • CWE-436 Interpretation Conflict weakness

References