CVE-2026-2880
@fastify/middie has an improper path normalization vulnerability
- State
- Published
- Severity
- 8.2 High
- Published
- Feb 27, 2026
- Updated
- Feb 27, 2026
- Reserved
- Feb 20, 2026
Description
A vulnerability in @fastify/middie versions < 9.2.0 can result in authentication/authorization bypass when using path-scoped middleware (for example, app.use('/secret', auth)).
When Fastify router normalization options are enabled (such as ignoreDuplicateSlashes, useSemicolonDelimiter, and related trailing-slash behavior), crafted request paths may bypass middleware checks while still being routed to protected handlers.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 8.2 High | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N | openjs |
Weaknesses
Affected Products
| Product | Versions |
|---|---|
@fastify/middie@fastify/middie |
|
References
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