CVE-2026-2880
Authorization Bypass in @fastify/middie via Path-Scoped Middleware
Publication date: 2026-02-27
Last updated on: 2026-03-19
Assigner: openjs
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| openjsf | @fastify/middie | to 9.2.0 (exc) |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-20 | The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability exists in @fastify/middie versions prior to 9.2.0 and allows an attacker to bypass authentication and authorization checks when using path-scoped middleware.
Specifically, when Fastify router normalization options like ignoreDuplicateSlashes, useSemicolonDelimiter, or trailing-slash behavior are enabled, crafted request paths can circumvent middleware protections while still reaching protected handlers.
How can this vulnerability impact me? :
This vulnerability can lead to unauthorized access to protected routes or resources within an application using the affected @fastify/middie versions.
Attackers can exploit crafted request paths to bypass authentication and authorization middleware, potentially exposing sensitive data or functionality that should be restricted.
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
I don't know
How can this vulnerability be detected on my network or system? Can you suggest some commands?
I don't know
What immediate steps should I take to mitigate this vulnerability?
I don't know