Next.js: Unbounded postponed resume buffering can lead to DoS
## Summary 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. ## Impact 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. ## Patches Fixed by enforcing size limits across all postponed-body buffering paths and erroring when limits are exceeded. ## Workarounds If upgrade is not immediately possible: - Block requests containing the `next-resume` header, as this is never valid to be sent from an untrusted client.
describes (1)
Related CVEs.
| ID | severity | exploitable | ||
|---|---|---|---|---|
| CVE-2026-27979US | high7.5 | — | ||
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 (cor… | ||||
references
External citations — patches, advisories, analysis.
- https://github.com/vercel/next.jsPACKAGE
- https://github.com/vercel/next.js/commit/c885d4825f800dd1e49ead37274dcd08cdd6f3f1WEB
- https://github.com/vercel/next.js/releases/tag/v16.1.7WEB
- https://github.com/vercel/next.js/security/advisories/GHSA-h27x-g6w4-24gqWEB
- https://nvd.nist.gov/vuln/detail/CVE-2026-27979ADVISORY
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