CVE-2026-27979
Next.js: Unbounded postponed resume buffering can lead to DoS
Impact
## 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.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| npm | next | >= 16.0.1, < 16.1.7 | 16.1.7 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Vercel | Next.Js | from 16.0.1 before 16.1.7 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/vercel/next.js/commit/c885d4825f800dd1e49ead37274dcd08cdd6f3f1
- https://github.com/vercel/next.js/releases/tag/v16.1.7
- https://github.com/vercel/next.js/security/advisories/GHSA-h27x-g6w4-24gq
- https://github.com/advisories/GHSA-h27x-g6w4-24gq
- https://nvd.nist.gov/vuln/detail/CVE-2026-27979