Next.js vulnerable to Denial of Service via connection exhaustion in applications using Cache Components
Published 11 May 2026 · Updated 10 Sept 2026
Affected packages
- Affected
- >=15.0.0 <15.5.16
- Fixed in
- 15.5.16
npm install next@15.5.16- Affected
- >=16.0.0 <16.2.5
- Fixed in
- 16.2.5
npm install next@16.2.5Details
Impact
Applications using Partial Prerendering through the Cache Components feature can be vulnerable to connection exhaustion through crafted POST requests to a server action. In affected configurations, a malicious request can trigger a request-body handling deadlock that leaves connections open for an extended period, consuming file descriptors and server capacity until legitimate users are denied service.
Fix
We now treat the header used for resuming Partial Prerendered requests as an internal-only header and strip it from untrusted incoming requests. This header should never be accepted directly from external clients.
Workarounds
If you cannot upgrade immediately, block requests that would be handled by Next.js if they contain the Next-Resume header at the edge.
Is GHSA-mg66-mrh9-m8jx in any of your client repos?
Checking one package by hand is fine. Checking it across forty client projects is not. NPMscan reads the lockfiles in every GitHub repo you pick, finds each project with an affected next, and gives you the command that fixes it.
References
Advisory data from OSV.dev (opens OSV.dev in a new tab), refreshed daily.