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HIGH

CVE-2026-64642

CVE-2026-64642 — Next.js: Middleware / Proxy bypass in App Router applications using Turbopack and single locale

Next.js is a React framework for building full-stack web applications. In versions 16.0.0 through 16.2.10, crafted requests targeting Next.js applications using App Router built with Turbopack and a single entry in config.i18n.locales can bypass middleware/proxy based authentication. This issue has been fixed in version 16.2.11.

Published Updated Sources: cvelistV5, GitHub_M

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the scoring sources call it.

Exploitation

Unreported

no source claims exploitation

EPSS

1%

chance of exploitation in 30 days

Affects

vercel

next_js

CVSS base

8.3

HIGH

CISA SSVC assessment

Three decision points CISA publishes for the CVEs it assesses · SSVC 2.0.3. A stakeholder decision, not a severity score.

CISA

Exploitation

None

none · proof-of-concept · active

Automatable

No

can an attacker script all four kill-chain steps

Technical impact

Partial

partial · total control of the vulnerable component

Affected scope

The catalog records vendors and products as separate lists, not pairs, so which product belongs to which vendor is not something this page can say.

Vendors (1)

vercel

Products (1)

next js

Every base score collected

Sources score independently and disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactSource
8.3CVSS 4.0HIGH——cvelistV5

Weakness & attack patterns

  • CWE-285

Attack patterns reported against this CVE. The ATT&CK techniques below are inferred from its weakness class.

  • T1574.010Hijack Execution Flow: ServicesFile Permissions Weakness
  • T1083File and Directory Discovery
  • T1562.003Impair Defenses: Impair Command History Logging

Detection

Read off the CVSS vector and the weakness class. Starting points, not rules we have tested.

  • Search application, proxy, and WAF logs for requests touching /proxy.

References

4 on the record

Elsewhere on this site

  • vercelevery CVE for this vendor
  • CWE-285other pages naming this weakness

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.