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.
Affected products
vercel: next.js
References5
- github.com/vercel/next.js/security/advisories/GHSA-m99w-x7hq-7v… Vendor Advisory
- github.com/vercel/next.js/commit/019628571641dec57aaf349ba0c360… Patch
- github.com/vercel/next.js/pull/96013 Issue TrackingPatch
- github.com/vercel/next.js/releases/tag/v15.5.21 ProductRelease Notes
- github.com/vercel/next.js/releases/tag/v16.2.11 ProductRelease Notes
Metrics
- CVSS 3.1
-
7.5
HIGH
Score source: NVD
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - CVSS 4.0
-
8.2
HIGH
Score source: CNA
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - EPSS — exploit probability
- 1% percentile: 59 · as of 13 November 2026
- CWE
- CWE-834
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.