CVE-2026-94485
Received Received - Intake

Next.js Development Server MCP Endpoint Exposure Leads to Information Disclosure

Publication date: 2026-10-02

Last updated on: 2026-10-02

Assigner: GitHub, Inc.

Description
Next.js is a React framework for building full-stack web applications. From 16.0.0 until 16.3.8, the `next dev` development server exposes a Model Context Protocol endpoint without reliably restricting cross-site requests. A malicious website visited by a developer can reach the endpoint and read the project's disk location, source code snippets from error reports, route inventory, and development logs. Production deployments do not serve this endpoint. This issue is fixed in version 16.3.8.

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Meta Information

Published
2026-10-02
Last Modified
2026-10-02
Generated
2026-10-02
AI Q&A
2026-10-02
EPSS Evaluated
N/A
NVD
CVE-2026-94485
EUVD
EUVD-2026-91673

Affected Vendors & Products

Showing 4 associated CPEs
Vendor Product Version / Range
vercel next.js to 16.3.8 (inc)
vercel next.js to 16.3.8 (exc)
vercel next.js 16.3.8
vercel next.js From 16.3.0 (inc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-346 The product does not properly verify that the source of data or communication is valid.

Attack-Flow Graph

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Executive Summary

This vulnerability affects Next.js versions 16.0.0 to 16.3.7. The development server exposes a Model Context Protocol endpoint that does not properly restrict cross-site requests. A malicious website visited by a developer can access this endpoint and read sensitive project data like disk location, source code snippets, route inventory, and development logs. The issue is fixed in version 16.3.8.

The vulnerability involves improper path parsing and validation in the MCP middleware, allowing unauthorized access to internal paths. The fix standardizes path handling and excludes certain internal asset paths from cross-site checks.

Impact Analysis

If you are a developer using Next.js versions 16.0.0 to 16.3.7, a malicious website you visit could access your project's sensitive data. This includes your project's file system location, source code snippets from error reports, and development logs. Attackers could use this information to gain deeper access to your project or steal intellectual property.

Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, potentially violating GDPR's data protection requirements or HIPAA's confidentiality rules. Exposure of source code, logs, or project structure may result in non-compliance with these regulations, leading to legal and financial penalties.

Mitigation Strategies

Upgrade Next.js to version 16.3.8 or later to address the vulnerability in the development server's Model Context Protocol endpoint.

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