CVE-2026-64642Network attack vector

Authentication bypass via omitted single-locale matcher

Published Jul 27, 2026 · Updated Jul 27, 2026

Improper authorization in Vercel Next.js 16.0.0 through 16.2.10 allows remote attackers to bypass middleware-based authentication. Turbopack's middleware matcher generation treats an i18n configuration with one locale as though i18n were absent, producing a route expression that crafted requests can evade. Exploitation requires App Router, a Turbopack build, one config.i18n.locales entry, and authorization enforced only by middleware or proxy logic; successful requests reach protected application data or actions.

CVSS severity8.3
High
EPSS probability1.01%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper authorization in Vercel Next.js 16.0.0 through 16.2.10 allows remote attackers to bypass middleware-based authentication. Turbopack's middleware matcher generation treats an i18n configuration with one locale as though i18n were absent, producing a route expression that crafted requests can evade. Exploitation requires App Router, a Turbopack build, one config.i18n.locales entry, and authorization enforced only by middleware or proxy logic; successful requests reach protected application data or actions.

The record

CVE
CVE-2026-64642
Published
Jul 27, 2026
Updated
Jul 27, 2026
Vendor
Vercel
Product
Next.js
Classifications
CWE-285, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 27, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 27, 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=>= 16.0.0, < 16.2.11

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Vercel · Next.jsversion=>= 16.0.0, < 16.2.11

Published CVSS scores

8.2NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
8.3GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA: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 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-285Improper Authorization
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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