CVE-2026-27979 PUBLISHED

Next.js: Unbounded postponed resume buffering can lead to DoS

Assigner: GitHub_M
Reserved: 25.02.2026 Published: 18.03.2026 Updated: 18.03.2026

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.

Metrics

CVSS Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
CVSS Score: 6.9

Product Status

Vendor vercel
Product next.js
Versions
  • Version >= 16.0.1, < 16.1.7 is affected

References

Problem Types

  • CWE-770: Allocation of Resources Without Limits or Throttling CWE