Next.js: Denial of Service in App Router using Server Actions

ALTO 7.5CVE-2026-64641 · GHSA-m99w-x7hq-7vfj · Published 27/07/2026 · updated 24/10/2026

Package	Affected versions	Patched versions
next.js vercel	`≥ 13.0.0, < 15.5.21≥ 16.0.0, < 16.2.11`	`15.5.2116.2.11`
next npm	`≥ 13.0.0, < 15.5.21≥ 16.0.0, < 16.2.11`	`15.5.2116.2.11`

Description

Impact

Crafted requests targeting Next.js applications using App Router with at least one Server Action can lead to excessive CPU usage blocking processing of further requests in the same process.

Workarounds

No workaround exists besides upgrading. Applications using Pages Router or not using Server Actions are not vulnerable.

NVD description

Next.js is a React framework for building full-stack web applications. In versions 13.0.0 through 15.5.20 and 16.0.0 through 16.2.10, crafted requests targeting Next.js applications using App Router with at least one Server Action can lead to excessive CPU usage blocking processing of further requests in the same process. This issue has been fixed in versions 15.5.21 and 16.2.11.

References

Running one of these products? Scan your site to see whether it exposes a vulnerable version.

Scan my site free