Summary
Next.js: Middleware / Proxy bypass in App Router applications using Turbopack and single locale
Workarounds
If you cannot upgrade immediately, enforce authorization in the page's server-side data path instead of relying solely on middleware.
Impact
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.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2026-64642? CVE-2026-64642 is a high-severity security vulnerability in next (npm), affecting versions >= 16.0.0, < 16.2.11. It is fixed in 16.2.11.
- Which versions of next are affected by CVE-2026-64642? next (npm) versions >= 16.0.0, < 16.2.11 is affected.
- Is there a fix for CVE-2026-64642? Yes. CVE-2026-64642 is fixed in 16.2.11. Upgrade to this version or later.
- Is CVE-2026-64642 exploitable, and should I be worried? Whether CVE-2026-64642 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-64642 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-64642? Upgrade
nextto 16.2.11 or later.