cvedb.io
CVE-2026-22031
HIGH · CVSS 8.4
EPSS exploitation probability: 0%
Published 2026-01-19T16:15:54.310 · Last modified 2026-06-17T10:19:23.437

Summary

@fastify/middie is the plugin that adds middleware support on steroids to Fastify. A security vulnerability exists in @fastify/middie prior to version 9.1.0 where middleware registered with a specific path prefix can be bypassed using URL-encoded characters (e.g., `/%61dmin` instead of `/admin`). While the middleware engine fails to match the encoded path and skips execution, the underlying Fastify router correctly decodes the path and matches the route handler, allowing attackers to access protected endpoints without the middleware constraints. Version 9.1.0 fixes the issue.

Affected products

fastify — fastify\/middie

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References

This product uses data from the NVD API but is not endorsed or certified by the NVD. Informational only; not professional security advice.