CVE-2026-14181Network attack vector

Remote process crash via malformed percent encoding

Published Jul 1, 2026 · Updated Jul 1, 2026

Uncaught exception in Fastify @fastify/middie 9.1.0 through 9.3.2 allows remote attackers to crash standalone-engine servers. Its normalize step passes malformed percent-encoded request paths to a decoder that throws synchronously, and the uncaught URIError terminates Node.js. Exposure requires direct use of middie.run through the standalone engine; the Fastify plugin path catches the exception, while an exposed engine remains unavailable until restart.

CVSS severity7.5
High
EPSS probability0.50%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uncaught exception in Fastify @fastify/middie 9.1.0 through 9.3.2 allows remote attackers to crash standalone-engine servers. Its normalize step passes malformed percent-encoded request paths to a decoder that throws synchronously, and the uncaught URIError terminates Node.js. Exposure requires direct use of middie.run through the standalone engine; the Fastify plugin path catches the exception, while an exposed engine remains unavailable until restart.

The record

CVE
CVE-2026-14181
Published
Jul 1, 2026
Updated
Jul 1, 2026
Vendor
Fastify
Product
@fastify/middie
Classifications
CWE-248, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 1, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 1, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=9.1.0 <9.3.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Fastify · @fastify/middieversion=9.1.0 <9.3.3

Published CVSS scores

7.5OpenJS FoundationCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-248Uncaught Exception
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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