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CVE

CVE-2026-6270

@fastify/middie vulnerable to middleware authentication bypass in child plugin scopes
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CVE

CVE-2026-6270

@fastify/middie vulnerable to middleware authentication bypass in child plugin scopes

@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.

Package Versions Affected

Package Version
patch Availability
No items found.

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CVSS Version

Severity
Base Score
CVSS Version
Score Vector
C
H
U
9.1
-
3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
C
H
U
0
-
3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
C
H
U
-

Related Resources

No items found.

References

https://cna.openjsf.org/security-advisories.html, https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/6xxx/CVE-2026-6270.json, https://github.com/fastify/fastify-express/security/advisories/GHSA-hrwm-hgmj-7p9c, https://github.com/fastify/middie/security/advisories/GHSA-72c6-fx6q-fr5w, https://nvd.nist.gov/vuln/detail/CVE-2026-6270

Severity

9.1

CVSS Score
0
10

Basic Information

Base CVSS
9.1
EPSS Probability
0.00498%
EPSS Percentile
0.40689%
Introduced Version
0
Fix Available
792d2f46ae68516d3122c9a4468a5748a34efb47

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