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CVE-2026-14181 Detail

Description

@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.


Metrics

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CVSS 4.0 Severity and Vector Strings:

NIST CVSS score
NIST: NVD
N/A
NVD assessment not yet provided.

References to Advisories, Solutions, and Tools

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URL Source(s) Tag(s)
openjs Vendor Advisory 
openjs Mitigation  Vendor Advisory 

Weakness Enumeration

CWE-ID CWE Name Source
CWE-248 Uncaught Exception openjs  

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Change History

3 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2026-14181
NVD Published Date:
07/01/2026
NVD Last Modified:
07/02/2026
Source:
openjs