CVE-2026-6270
@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.
Scoring
- Severity
- CRITICAL
- CVSS base score
- 9.1
- CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
- EPSS probability
- 0.50%
- CWE
- CWE-436
- Published
- 2026-04-16
- Last modified
- 2026-04-16
Affected products
- @fastify/middie @fastify/middie
- @fastify/middie @fastify/middie
Weakness type
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