CVE-2026-6270
This allows unauthenticated requests to reach routes defined in child plugin scopes, bypassing authentication and authorization checks.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.50%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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.
- CVSS 3.1
- 9.1 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
- EPSS
- 0.50% probability · 41th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-436
- Affected
- fastify/fastify\/middie
- Source
- ce714d77-add3-4f53-aff5-83d477b104bb
References
- https://cna.openjsf.org/security-advisories.htmlVendor Advisory
- https://github.com/fastify/fastify-express/security/advisories/GHSA-hrwm-hgmj-7p9cExploit, Mitigation, Vendor Advisory
- https://github.com/fastify/middie/security/advisories/GHSA-72c6-fx6q-fr5wVendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.