Next.js has information disclosure in development server's Model Context Protocol endpoint
Published 7 Oct 2026 · Updated 7 Oct 2026
Affected package
- Affected
- >=16.0.0 <16.3.8
- Fixed in
- 16.3.8
npm install next@16.3.8Details
The Next.js development server (next dev) exposes a Model Context Protocol endpoint that does not verify which website a request originates from, allowing a malicious website visited by the developer to read sensitive development data — including the project's location on disk, source code snippets from error reports, the route inventory, and development logs. Only applications run with next dev are affected. Production deployments do not serve this endpoint.
Is GHSA-39w2-rjm5-chcv 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.