CVE-2026-33804 (GCVE-0-2026-33804)

Vulnerability from cvelistv5 – Published: 2026-04-16 13:56 – Updated: 2026-04-16 14:41
VLAI?
Title
@fastify/middie vulnerable to middleware bypass via deprecated ignoreDuplicateSlashes option
Summary
@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.
Severity ?
7.4 (High)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
CWE
  • CWE-436 - Interpretation Conflict
Assigner
References
Impacted products
Vendor Product Version
@fastify/middie @fastify/middie Affected: 0 , < 9.3.2 (semver)
Unaffected: 9.3.2 (semver)
Create a notification for this product.
Credits
FredKSchott mcollina climba03003 UlisesGascon
Show details on NVD website
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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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