What is CVE-2026-27979?

CVE-2026-27979 is a high-severity vulnerability in Vercel Next.js, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 7.5/10. Published 2026-03-18.

How severe is CVE-2026-27979?

High severity. CVSS v3 base score is 7.5 out of 10.

Resource exhaustion in Vercel Next.js

CVE-2026-27979

Next.js is a React framework for building full-stack web applications. Starting in version 16.0.1 and prior to version 16.1.7, a request containing the `next-resume: 1` header (corresponding with a PPR resume request) would buffer request bodies without consistently enforcing `maxPostponedStateSize` in certain setups. The previous mitigation protected minimal-mode deployments, but equivalent non-minimal deployments remained vulnerable to the same unbounded postponed resume-body buffering behavior. In applications using the App Router with Partial Prerendering capability enabled (via `experimental.ppr` or `cacheComponents`), an attacker could send oversized `next-resume` POST payloads that were buffered without consistent size enforcement in non-minimal deployments, causing excessive memory usage and potential denial of service. This is fixed in version 16.1.7 by enforcing size limits across all postponed-body buffering paths and erroring when limits are exceeded. If upgrading is not immediately possible, block requests containing the `next-resume` header, as this is never valid to be sent from an untrusted client.

Published 2026-03-18 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.008 (56.2th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 56th percentile — 56.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.007 · newest: 0.008 · change: +0.002

Affected products

Vercel Next.js — versions >= 16.0.1, < 16.1.7

Weakness classification (CWE)

CWE-770 — Allocation of Resources Without Limits or Throttling

References

github.com/vercel/next.js/security/advisories/GHSA-h27x-g6w4-24gq (Mitigation, Vendor Advisory)
github.com/vercel/next.js/commit/c885d4825f800dd1e49ead37274dcd08cdd6f3f1 (Patch)
github.com/vercel/next.js/releases/tag/v16.1.7 (Release Notes)

Frequently asked questions

What is CVE-2026-27979?: CVE-2026-27979 is a high-severity vulnerability in Vercel Next.js, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 7.5/10. Published 2026-03-18.
How severe is CVE-2026-27979?: High severity. CVSS v3 base score is 7.5 out of 10.