Critical severity9.1NVD Advisory· Published Apr 16, 2026· Updated May 14, 2026
CVE-2026-6270
CVE-2026-6270
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.
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
@fastify/middienpm | < 9.3.2 | 9.3.2 |
Affected products
2Patches
Vulnerability mechanics
References
5- github.com/fastify/fastify-express/security/advisories/GHSA-hrwm-hgmj-7p9cnvdExploitMitigationVendor AdvisoryWEB
- cna.openjsf.org/security-advisories.htmlnvdVendor AdvisoryWEB
- github.com/advisories/GHSA-72c6-fx6q-fr5wghsaADVISORY
- github.com/fastify/middie/security/advisories/GHSA-72c6-fx6q-fr5wnvdVendor AdvisoryWEB
- nvd.nist.gov/vuln/detail/CVE-2026-6270ghsaADVISORY
News mentions
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