Summary
Next.js: Unbounded Server Action payload in Edge runtime
Workarounds
If you cannot upgrade, ensure your hosting provider limits the request's body size. 5 MiB should be allowed at max by your hosting provider.
Impact
Requests targeting Next.js applications using App Router with at least one Server Action can lead to excessive memory consumption if that Server Actions uses the Edge runtime
The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap. Typical impact: resource exhaustion leading to denial of service.
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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next to 15.5.21 or later; next to 16.2.11 or later
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2026-64646? CVE-2026-64646 is a medium-severity allocation of resources without limits or throttling vulnerability in next (npm), affecting versions >= 13.0.0, < 15.5.21. It is fixed in 15.5.21, 16.2.11. The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap.
- Which versions of next are affected by CVE-2026-64646? next (npm) versions >= 13.0.0, < 15.5.21 is affected.
- Is there a fix for CVE-2026-64646? Yes. CVE-2026-64646 is fixed in 15.5.21, 16.2.11. Upgrade to this version or later.
- Is CVE-2026-64646 exploitable, and should I be worried? Whether CVE-2026-64646 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-2026-64646 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-2026-64646?
- Upgrade
nextto 15.5.21 or later - Upgrade
nextto 16.2.11 or later
- Upgrade