CVE-2026-6414Network attack vector

Unauthenticated file disclosure via encoded path separators

Published Apr 16, 2026 · Updated Apr 16, 2026

URL-encoding mishandling in Fastify @fastify/static 8.0.0 through 9.1.0 allows remote attackers to read guarded static files. The plugin decodes %2F before filesystem resolution while the router treats it literally, so an encoded separator evades the matching route guard. Exposure requires an application to rely on route-based middleware or guards to restrict files inside the configured static root.

CVSS severity5.9
Medium
EPSS probability0.41%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

URL-encoding mishandling in Fastify @fastify/static 8.0.0 through 9.1.0 allows remote attackers to read guarded static files. The plugin decodes %2F before filesystem resolution while the router treats it literally, so an encoded separator evades the matching route guard. Exposure requires an application to rely on route-based middleware or guards to restrict files inside the configured static root.

The record

CVE
CVE-2026-6414
Published
Apr 16, 2026
Updated
Apr 16, 2026
Vendor
Fastify
Product
@fastify/static
Classifications
CWE-177, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 16, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 16, 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=8.0.0 <9.1.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Fastify · @fastify/staticversion=8.0.0 <9.1.1

Published CVSS scores

5.9OpenJS FoundationCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-177Improper Handling of URL Encoding (Hex Encoding)
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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