CVE-2026-6270
@fastify/middie vulnerable to middleware authentication bypass in child plugin scopes
- State
- Published
- Severity
- 9.1 Critical
- Published
- Apr 16, 2026
- Updated
- Apr 16, 2026
- Reserved
- Apr 14, 2026
Description
@fastify/middie versions 9.3.1 and earlier do not register inherited middleware directly on child plugin engine instances. When a Fastify application registers authentication middleware in a parent scope and then registers child plugins with @fastify/middie, the child scope does not inherit the parent middleware. This allows unauthenticated requests to reach routes defined in child plugin scopes, bypassing authentication and authorization checks. Upgrade to @fastify/middie 9.3.2 to fix this issue. There are no workarounds.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 9.1 Critical | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N | openjs |
Weaknesses
- CWE-436 Interpretation Conflict
Affected Products
| Product | Versions |
|---|---|
@fastify/middie@fastify/middie |
|
References
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