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CVE-2026-14181

@fastify/middie standalone engine vulnerable to Denial of Service via malformed percent-encoded paths

CVSS 7.5 HIGHCWE-248
Vexday Risk Score
18Bajo
Decisión SSVC (CISA)
Track
Sin señal de explotación → monitorear
CVSS 7.5EPSS KEV nãoPoC Nuclei Metasploit Patch
Ciclo de vida
01 jul 2026Publicada en NVD
Recomendación: Monitorear — sin señal de explotación por ahora.
@fastify/middie versions 9.1.0 through 9.3.2 fail to guard the URL normalization step used by the standalone engine when incoming request paths contain malformed percent-encoded sequences. Inputs such as an incomplete percent escape or a truncated multibyte sequence cause the underlying decoder to throw synchronously, and the exception escapes the middie normalize step and terminates the Node.js process. The bypass affects applications that call middie.run directly on the standalone engine API, causing an immediate denial of service for all connected clients until restart. Applications using the Fastify plugin path are not affected because Fastifys error handler catches the exception. Patches: upgrade to @fastify/middie 9.3.3. Workarounds: migrate from the standalone engine API to the Fastify plugin path, where the framework error handler catches the exception.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H